An old trick by ex-spouses receiving alimony is to avoid remarriage while enjoying all of its trappings with a new beau. That’s why divorce settlements often include clauses that can stanch the flow of cash upon a showing that an ex is shacking up.

A state appeals court on Thursday offered some guidance on the quantum of evidence needed, ruling that staying at a lover’s house a couple of nights a week, keeping some clothes there and occasionally receiving the odd piece of mail there does not cohabitation make.

According to the opinion in Gould v. Gould, A-4757-10, the couple was married in 1995, had three children and divorced in 2009. Under the terms of their divorce settlement, Eric Gould is to pay Robin Gould limited-duration alimony until 2019. A paragraph in the settlement agreement allows Eric to ask that he be allowed to stop paying alimony if Robin cohabitates with someone else.

Robin had been seeing another man, identified only as M.J., since 2008, a year before the divorce became final.

In January 2011, Eric asked Superior Court Judge Catherine Enright to eliminate or modify his alimony obligation based on his allegation that Robin was now cohabitating with M.J. At the very least, Eric said he was entitled to discovery or a plenary hearing.

Eric claimed that M.J. kept a separate “sham residence,” but actually lived with Robin. Eric said M.J. kept a closet full of clothes at Robin’s house, helped with the children while they were with her and went on vacations with Robin and the children. Eric once found a piece of mail addressed to M.J. in Robin’s mailbox.

Eric hired a private investigator, who staked out Robin’s house for six nights. M.J. was there for at least some period every night and stayed overnight when the children were with Eric.

Robin acknowledged the romantic relationship and said M.J. did occasionally help with the children and go on vacation with them. But she said he only kept clothes at her house so he could change after using their exercise equipment. The two, Robin said, did not share finances and he did not help pay her bills. They did not, she said, share a marital-type relationship.

Enright found Eric had not presented enough evidence to establish a prima facie case for her to order discovery or a change in his alimony obligations.

Appellate Division Judges Margaret Hayden and Allison Accurso agreed with Enright that there was no rebuttable evidence of cohabitation. They said the private investigator’s findings provided only a “brief snapshot” of the relationship between Robin and M.J.

“[P]laintiff’s evidence, that defendant and M.J. spend considerable time together, as people in romantic relationships often do, is not sufficient to establish a prima facie case that they share a marital-type relationship,” they added.

The judges refined the doctrine of Konzelman v. Konzelman, 158 N.J. 185 (1999), which requires a showing that a couple shares an “intimate” and “stable” relationship that not only involves living together, but also includes sharing finances, household chores and generally being recognized by their friends and family as being in a committed relationship with a sense of permanency.

Robin’s lawyer, Millburn solo Janet Pennisi, declines to comment. Eric’s lawyer, Madeline Marzano-Lesnevich, of Hackensack’s Lesnevich & Marzano-Lesnevich, did not return a telephone call seeking comment.