Infidelity (synonyms include: cheating, straying, adultery (when married), being unfaithful, or having an affair) is a violation of a couple's assumed or stated contract regarding emotional and/or sexual exclusivity.
Other scholars define infidelity as a violation according to the subjective feeling that one's partner has violated a set of rules or relationship norms; this violation results in feelings of anger, jealousy, sexual jealousy, and rivalry.
What constitutes an act of infidelity depends upon the exclusivity expectations within the relationship. In marital relationships, exclusivity expectations are commonly assumed, although they are not always met. When they are not met, research has found that psychological damage can occur, including feelings of rage and betrayal, lowering of sexual and personal confidence, and damage to self-image.
Depending on the context, men and women can experience social consequences if their act of infidelity becomes public. The form and extent of these consequences are often dependent on the gender of the unfaithful person.