Infidelity has a variety of definitions, depending on the couple or individual. For most people, marital cheating is strictly defined as one partner having sexual relations — viewed as sexual intercourse and/or oral sex — with a third party. For some, infidelity also applies to nonsexual situations, for example, when a married man forms a deep emotional bond with a woman to whom he is not married, or when a married woman flirts or enjoys personal conversations with a male coworker. Yet there are married men and women who give their partners a wide berth to form close friendships with members of the opposite sex, as long as the interactions remain hands off.
However you define infidelity, when it occurs (that is, when your partner violates your expectations about what is appropriate in relationship to others) you will most likely feel betrayed. This is true whether or not you ever sat down as a couple to discuss and define what each of you means by cheating. Having this conversation is an important conversation to have early on in any marriage, and it's the only way you'll be able to arrive at common definitions and expectations. Here are some considerations to assist you in this process.
In the American Sexual Survey conducted by The National Opinion Research Center at The University of Chicago, researchers found that 22 percent of married men and 15 percent of married women had had at least one extramarital affair. According to this survey of ten thousand married people conducted over twenty years, most cheating happens three to five years into a marriage by a man dissatisfied with sex, or by a woman who feels emotionally deprived in her marriage.