A situation when one of the partners in a married couple (for this tag - woman) is not satisfied with sexual, personal or any other aspect of their partner, and they're taking action of satisfying those needs through the other person. Of course, the other partner doesn't know about this, because the partner is lying to them about their current location / timetable / needs and etc.

Very often such situation in a couple causes argues, fights, scandals or, if it'll get any worse, a divorce.