Judgments, Supreme Court, New York County (Saralee Evans, J.), entered July 3 and July 31, 2006, awarding plaintiff wife maintenance arrears and attorneys’ fees, and bringing up for review prior orders, including that entered March 14, 2006, which, after a hearing, granted plaintiffs motion to enforce the *446parties’ settlement agreement and denied defendant’s cross motion for summary judgment terminating his maintenance obligation under that agreement, and directed defendant to resume such payments and pay arrears, affirmed, without costs. Appeals from the orders dismissed, without costs, as subsumed in the appeals from the judgments.
The issue on appeal is whether plaintiff Linda Graev forfeited her right to maintenance because of what defendant Lawrence Graev alleges was “cohabitation” with a nonparty (“MP”) for “sixty (60) substantially consecutive days” in the summer of 2004. Based on the evidence in the record, plaintiffs relationship with MP did not constitute “cohabitation” as this term has been construed. Accordingly, we affirm the judgments appealed.
Linda and Lawrence Graev were married for approximately 24 years. In April of 1997, they executed a settlement agreement, which was incorporated but not merged into their divorce judgment in June 1997. Article IV of the settlement agreement concerned maintenance and provided that Mr. Graev would pay his ex-wife $10,000 per month. This was later adjusted to $11,000 per month pursuant to a cost-of-living provision. The agreement provided that the maintenance obligation would terminate on August 10, 2009, or upon the occurrence of any one of four “Termination Events.” Those events, set forth in section 4.2, were:
“(a) the death of the Wife;
“(b) the death of the Husband;
“(c) The remarriage of the Wife regardless if such remarriage is void or voidable; [or]
“(d) the cohabitation of the Wife with an unrelated adult for a period of sixty (60) substantially consecutive days.”
The term “cohabitation” is not defined in the agreement.
On September 7, 2004, Mr. Graev sent Mrs. Graev a letter stating that he would no longer pay her maintenance because of her “cohabitation” with MP for 60 substantially consecutive days. Mrs. Graev moved to enforce the divorce judgment and for an order directing defendant to resume paying maintenance plus arrears, as well as legal expenses pursuant to section 21.1 of the settlement agreement. Mr. Graev cross-moved for summary judgment allowing him to cease paying maintenance. He further requested $500,000 in liquidated damages pursuant to section 14.2 of the settlement agreement,* expenses, costs and attorneys’ fees.
*447Mr. Graev’s motion was supported with the affidavit of a private investigator. He stated that he and his team had been hired by Mr. Graev to conduct surveillance of Mrs. Graev’s Connecticut house for nine hours a day over a 63 day period during July and August of 2004. The team confirmed that Mrs. Graev lived on Keeler Road in Bridgewater and that MP had a home nearby, on Brown Brook Road in Southbury. The investigator also affirmed that MP’s car was in Mrs. Graev’s driveway at 5:00 a.m. on virtually all of the 63 days that they conducted surveillance. The investigator related that there was a nine-day period when the “newspapers piled up” at Ms. Graev’s residence. During that same nine-day period, “there were no signs of activity” at MP’s residence.
In reply, Mrs. Graev denied that she “cohabitated” or lived with MR She stated that her primary residence was and is in New York City, where she works full time from September to June of every year. She stated she has a summer house in Connecticut, and that MP owns his own home near hers. Mrs. Graev affirmed that MP stayed with her for approximately two weeks between the sale of one home in Connecticut and his purchase of a new home.
In February 2005, the IAS court determined that Mr. Graev was entitled to a hearing to determine whether there had been a “terminating event.” Prior to the hearing, the husband moved for leave to introduce evidence, including expert testimony, as to the meaning of the term “cohabitation.” It was his position that the term was ambiguous. Thus, he sought to offer testimony as to “how usage or custom has affected and influenced the meaning of the term.” He also wanted to present evidence showing the circumstances surrounding the dissolution of the marriage because, he asserted, they were instructive as to the parties’ intent when they included the term in their agreement. The IAS court denied the motion. It found that a prior ruling in this action, that the term “cohabitation” was not ambiguous, was law of the case. While it does not affect our analysis, it bears noting that the prior IAS court ruling did not explicitly state that the term “cohabitation” was unambiguous, but instead that the term had not been construed in the narrow manner that Mrs. Graev suggested.
A hearing was conducted over seven days between September 14 and December 1, 2005. Testimony was taken from Mr. Graev, Mrs. Graev, MR MP’s son, and Mrs. Graev’s doctor. Mr. Graev testified that he first met MP in June 2003, when he and Mrs. Graev attended their daughter’s engagement party. He stated that MP also accompanied Mrs. Graev to two other family par*448ties in 2004. Mr. Graev also described how he had hired a private investigator to monitor Mrs. Graev’s house in Connecticut over the summer of 2004.
The head of the private investigation team was not called to testify at the hearing because he was out of state, but the parties agreed to introduce his surveillance tapes and deposition testimony. The surveillance evidence included photos and videos of the driveway area of plaintiffs summer house from 5:00 to 9:00 a.m., and 7:00 p.m. to midnight for 63 days. No surveillance was conducted from midmorning until the evening on any of the days in question. However, the evidence shows that MP’s car was in Mrs. Graev’s driveway “virtually all” of the mornings and nights that the investigators were watching her house.
Mrs. Graev took the stand and gave her address as a location on Fifth Avenue in Manhattan. She stated that she worked full time as a reading specialist at a private school in the City. Mrs. Graev informed the court that her New York address was where she received all of her mail, including all bills for both of her homes. Mrs. Graev stated that her work begins after Labor Day and ends in the middle of June. She testified that she stays in Manhattan during the week throughout the school year, and that she goes to her house in Connecticut most weekends and during summer vacation. Mrs. Graev said she pays taxes in New York. She added that she votes in New York.
Mrs. Graev recounted that she met MP in Connecticut in October 2002, years after her divorce. She said that they began dating shortly thereafter, and that their relationship became romantic in January 2003. She testified that they are exclusive companions. However, Mrs. Graev stated that she and MP have never discussed living together, and they do not presently commingle their finances, nor have they made any plans to do so. She testified that the two spent many nights together in Connecticut, where they both own separate homes. Mrs. Graev also recounted that she made frequent trips into New York during summers to attend to chores, and that when she did so, she went alone.
Mrs. Graev testified that throughout her relationship with Ml^ they split the costs of all shared items, such as meals, movies, and travel. She said that MP helped her with planting in her garden on a few occasions, and that he once helped her to paint a fence. However, she said that the two took care of their own separate household chores. Mrs. Graev testified that she employs both a housekeeper and a gardener at her Connecticut house. Mrs. Graev averred that MP makes no financial contribution to the upkeep of her home, nor she for the maintenance of his home.
*449Mrs. Graev explained that the couple’s overnight visits were more frequent in the summers because she was on vacation and spending the majority of her time in Connecticut. She related that the first summer the two were dating, 2003, MP spent “a couple of nights during the week” and “one night on the weekend” at Mrs. Graev’s house. It was her recollection that during the summer of 2004, she and MP spent more nights together. However, Mrs. Graev also testified that she was planning her daughter’s wedding during that summer, which required her to travel to New York City frequently.
MP testified that he is a retired school administrator and lives in Connecticut. His description of his relationship with Mrs. Graev was substantially similar to Mrs. Graev’s. He also stated that from August 16 to August 28, 2004, between the sale of one home in the area and the purchase of another, he stayed with Mrs. Graev. During that period, he also stored some of his property in plaintiff’s garage. MP testified that he did not have a key to Mrs. Graev’s home, but that she had told him the location of a spare key. He said he used this key while he stayed with Mrs. Graev between his house closings.
MP’s 25-year-old son testified that he had lived with his father for part of the summer of 2004. The son recalled frequently having dinner with his dad, and occasionally with Mrs. Graev. He also stated that his father spent a substantial part of his days painting, a hobby which he enjoyed. He testified that his father did his painting at his own house. MP’s son stated that he did not know much about this litigation, other than the fact that it concerned “cohabitation.”
The final witness at the hearing was Mrs. Graev’s psychiatrist. He was qualified as an expert in psycho-pharmacology and had been treating Mrs. Graev for depression since 1998. He stated that he had prescribed medication for her, which had. adverse sexual side effects.
After hearing the testimony and examining the evidence, the IAS court concluded that there had been no “cohabitation” and that Mrs. Graev had not forfeited her right to maintenance. Mr. Graev appeals. He contends that the term “cohabitation” is ambiguous, and that there are no New York cases which define the term. He argues that he should have been allowed to introduce extrinsic evidence as to the parties’ intent when they included this term in their settlement agreement. He also contends that expert testimony should have been admitted to aid the trial court in understanding the term “cohabitation,” as understood in “modem society.”
Mrs. Graev counters that New York courts have uniformly *450construed “cohabitation” as synonymous with “living together.” She argues that this includes three elements: (1) sharing a residence, (2) sharing expenses, and (3) functioning as an economic unit. Because none of these elements was present here, she urges that we affirm the judgments appealed.
Domestic Relations Law § 248 allows the court to eliminate maintenance upon “proof that the wife is habitually living with another man and holding herself out as his wife.” This statutory two-part test has been rigidly applied, requiring that each prong be proven (Northrup v Northrup, 43 NY2d 566 [1978]; see also Markhoff v Markhoff, 225 AD2d 1000 [1996], lv denied 88 NY2d 807 [1996] [maintenance terminated where both statutory elements were met]).
For example, the Court of Appeals has rejected a. husband’s application to terminate his maintenance obligation to a former spouse because the second of the two requirements of Domestic Relations Law § 248 had not been met. In Matter of Bliss v Bliss (66 NY2d 382 [1985]), the former wife had been living with another man for 12 years, but there was no evidence that she was representing herself as married to her companion (see also Szemansco v Szemansco, 11 AD3d 787 [2004]; Matter of Messineo v Messineo, 196 AD2d 826 [1993]; cf. Karl v Karl, 138 AD2d 354, 355-357 [1988, Weinstein, J., concurring], lv denied 72 NY2d 803 [1988]).
Notwithstanding these strict statutory requirements, the parties to a divorce can, by agreement, alter the terms of Domestic Relations Law § 248. They can, if they choose, eliminate the statutory requirement that the wife “holds herself out as the other man’s wife” (see Scharnweber v Scharnweber, 65 NY2d 1016,1017 [1985]; see also Smith v Smith, 233 AD2d 830 [1996]; Pesa v Pesa, 230 AD2d 837 [1996]).
Agreements modifying Domestic Relations Law § 248 are uniformly viewed as contracts subject to the principles of contract construction and interpretation (Matter of Meccico v Meccico, 76 NY2d 822, 823-824 [1990]; Rainbow v Swisher, 72 NY2d 106, 109 [1988]). As with any contract the “best evidence of what parties to a written agreement intend is what they say in their writing” (Slamow v Del Col, 79 NY2d 1016, 1018 [1992]). Accordingly, “a written agreement that is complete, clear and unambiguous on its face must be enforced according to the plain meaning of its terms” (Greenfield v Philles Records, 98 NY2d 562, 569 [2002]).
Whether a contractual term is ambiguous must be determined by looking within the four corners of the document and not to extrinsic sources (Kass v Kass, 91 NY2d 554, 566 [1998]; Matter *451of Stravinsky, 4 AD3d 75, 81 [2003]); extrinsic evidence cannot be used to create an ambiguity in an agreement, but only to resolve an ambiguity (Kass, 91 NY2d at 568). That one party to the agreement may attach a particular, subjective meaning to a term that differs from the term’s plain meaning does not render the term ambiguous (see Moore v Kopel, 237 AD2d 124, 125 [1997]).
Here, the settlement agreement provided that Mrs. Graev would forfeit her right to maintenance if she “cohabit[ed] . . . with an unrelated adult for a period of sixty (60) substantially consecutive days.” A review of New York case law shows that in the context of these types of separation agreements, the term cohabitation has a plain meaning which contemplates changed economic circumstances, and is not ambiguous. Just as it is sensible to presume that when the Legislature amends a statute it is aware of all judicial decisions construing it (see People v Robinson, 95 NY2d 179, 184 [2000]), it is also sensible to presume that attorneys using a term such as “cohabitation” in a separation agreement are aware of the judicial decisions construing the term.
The dissent presumes that these parties intended to use the dictionary definition of “cohabitation.” However, it fails to explain why judicial decisions giving a distinct meaning to the term should be ignored. For example, the Second Department recently discussed the meaning of “cohabitation” when affirming the denial of a husband’s motion to terminate his maintenance obligation. Rejecting a claim that the phrase “cohabitation of the Wife with an unrelated male” was ambiguous, the court stated: “As interpreted by New York courts, the term ‘cohabitation’ entails a relationship between a former wife and an unrelated male who live together in the same residence and share household expenses or ‘function as an economic unit’ (see Matter of Ciardullo v Ciardullo, 27 AD3d 735, 736 [2006]; Matter of Emrich v Emrich, 173 AD2d 818, 819 [1991]; Scharnweber v Scharnweber, 105 AD2d 1080, 1080 [1984], affd 65 NY2d 1016, 1017 [1985]).” (Clark v Clark, 33 AD3d 836, 837, 838 [2006].)
While the facts in this case are different from Clark, where the wife and the parties’ children had moved into a “commune” with another family soon after the divorce was finalized, the Clarks’ settlement agreement was similar to the Graevs’ in that it provided for termination of maintenance if the wife “cohabitat[ed] . . . with an unrelated male” (id. at 837). Here, as in Clark, Mr. Graev had the burden of establishing an event that terminated his maintenance obligation. He did not meet this burden.
*452The Second Department’s decision in Ciardullo is also instructive. The event which would terminate maintenance in the Ciardullos’ agreement was “habitually living” or “establishing a residence with a man.” (27 AD3d at 736.) Adopting the same analysis articulated in Clark, the court held that the wife and her boyfriend were not “habitually living” together because they maintained separate residences and neither shared expenses nor functioned as an economic unit (27 AD3d at 736).
New York courts have uniformly construed the term “cohabitation,” when used in agreements governing the modification of support obligations, as more than a romantic relationship or series of nights spent together. It is the dissent’s position that the economics of Mrs. Graev’s relationship with MP are irrelevant. However, New York case law interpreting similar clauses looks to the sharing of finances to determine whether parties are “cohabitating.” This analysis makes sense, given the underlying question of whether the relationship at issue is the type of “changed circumstances” which would render a support obligation unjust. While many of the challenged agreements have included temporal limits, the term “cohabitation” has required the additional showing of an economic relationship akin to a shared possessory interest in one home. Such an interest can be proven with evidence that two people keep their personal belongings and receive their mail at the same address (see Salas v Salas, 128 AD2d 849 [1987], lv dismissed 70 NY2d 747 [1987]). Of course, the parties were free to condition support as they pleased, or to restrict the dependent spouse’s postdivorce intimate relations. Had the Graevs desired to ascribe a different meaning to “cohabitation,” they were free to do so by using appropriate language in their agreement.
The dissent faults our reliance upon Clark, Ciardullo, Emrich (lv denied 78 NY2d 860 [1991]), and Scharnweber, four unanimous appellate division cases providing that “cohabitation” requires a sharing of expenses. While the dissent correctly observes that these cases all originated in other departments, there is no First Department authority which conflicts with their holdings. Moreover, nothing in the Court of Appeals affirmance in Scharnweber indicates a rejection of the Appellate Division’s holding that sharing of household expenses or functioning as an economic unit constitute elements of “cohabitation.”
There is ample evidence that Mrs. Graev and MP spent in excess of 60 nights together during the summer of 2004, and Mrs. Graev does not deny that her relationship with MP was romantic. The number of nights that MP slept at Mrs. Graev’s *453Connecticut summer house is not decisive, because he had his own home and there is absolutely no evidence that the couple shared household expenses or functioned as a single economic unit. In other words, there was no showing that they “cohabited,” as New York courts have consistently construed this term in this context. Mrs. Graev and MP did not live together. MP had his own residence, minutes from Mrs. Graev’s summer house. MP kept all of his personal belongings at his own home, and he received his mail at that address. Mrs. Graev and MP did not assume each others’ expenses or share bank accounts or credit cards. Mrs. Graev received all of her bills, paid her taxes, and voted in New York.
Mr. and Mrs. Graev agreed to dissolve their marriage, and the law requires that they adhere to the contract that they negotiated when they did so.
In Hernandez v Robles (7 NY3d 338, 358 [2006]), the New York Court of Appeals recognized the economic realities which distinguish a marriage from all other forms of committed relationships: “It is undisputed that the benefits of marriage are many. . . . some of the most important [include]: Married people receive significant tax advantages, rights in probate and intestacy proceedings, rights to support from their spouses both during the marriage and after it is dissolved, and rights to be treated as family members in obtaining insurance coverage and making health care decisions.” (Emphasis added.) Consistent with that policy and the unambiguous terms of the parties’ agreement herein, the motion court properly determined that Mr. Graev had not established a “terminating event” requiring Mrs. Graev to forfeit her right to maintenance. Concur—Mazzarelli, J.P., Williams and McGuire, JJ.
Section 14.2, an in terrorem provision, provides for a $500,000 penalty to be imposed upon any party who attempts to vacate or breach the contract.