People get divorced and sometimes one person has to pay spousal support (maintenance) to the other spouse for a specified period of time in a specified amount so long as the recipient is unmarried. The Domestic Relations Law provides that maintenance can be terminated due to cohabitation and holding themselves out as husband and wife. Proving the above has been found to be very difficult for a variety of reasons.
Therefore, the language that is utilized if you have a divorce settlement agreement is very important. Divorce lawyers know how hard it is to end maintenance payments because the ex-spouse is living with someone else and therefore the key is to have good defining terms as to what is considered a legitimate reason to terminate maintenance.
Many lawyers will utilize language that provides if you live with a person unrelated by blood or marriage for a period of thirty (30) consecutive days that maintenance may be terminated. Note that this language does not require proof of holding themselves out as husband and wife, instead it is time based.
Sneaky spouses then would have their "friend" maintain an alternate residence and after 28 days of living together have the person sleep elsewhere for two nights and affirmatively state that the period of 30 consecutive days did not occur. The lawyers then combated back and drafted language that also terminated maintenance if the people lived together for 60 non-consecutive days in any period of six months.
As you can see the language put into the stipulation must be carefully drafted to provide a termination for this type of conduct. There are other variations of this language both as to definition and time period. If you are the paying spouse you want to make sure you are protected and if you are the recipient spouse you prefer rigorous language that will be hard to prove.