Adultery is a ground for divorce in New York, defined as voluntary sexual intercourse between a spouse and someone not their spouse. Proving New York Divorce Laws Adultery requires evidence such as testimony from a third party, photographic or video evidence, admissions by the defendant, or circumstantial evidence. If proven, it can lead to a fault-based divorce, property division, spousal support, and child custody. Defenses to adultery include consent, connivance, and condonation. The New York State Unified Court System, New York City Bar Association, American Academy of Matrimonial Lawyers, and National Center for State Courts provide resources for understanding adultery in New York divorce laws.