A court may, in its discretion, modify the final judgment, or any orders made with respect to the final judgment, by annulling the provisions for the wife's support upon proof that the wife is habitually living with another man and holding herself out as his wife, though not married to him. The circumstances under which relief can be obtained under the NY law are limited: the wife must not only be habitually living with another man, she must be holding herself as her husband.
I would also check your Stipulation and/or Judgment of Divorce, and see if there is a cohabitation provision, whereby maintenance would be terminated if your wife cohabited with another. If you have a cohabitation clause that differs from the NY law, then you might have a chance to terminate maintenance under the cohabitation clause in your Stipulation or Judgment.
Regardless, it is probably wise to contact an attorney to go over the specific facts of your case and whether based on your facts the Court would terminate maintenance.