In many intimate relationships in many cultures there is usually an express or implied expectation of exclusivity, especially in sexual matters. Infidelity (colloquially known as cheating) most commonly refers to a breach of the expectation of sexual exclusivity.
Infidelity can occur in relation to physical intimacy and/or emotional intimacy. The impact of infidelity is said to be not only about sex outside the relationship, but also about trust, betrayal, lying and disloyalty. Sexual infidelity by a marriage partner is commonly called philandery, adultery, or an affair.
What constitutes an act of infidelity varies between and within cultures and depends on the type of relationship that exists between people. Even within an open relationship, infidelity may arise if a partner in the relationship acts outside of the understood boundaries of that relationship.
Emotional infidelity is emotional involvement with another person, a process which leads one’s partner to channel emotional resources, such as romantic love, time, and attention, to someone else. With the association of multi-user dimensions the level of intimate involvement has extended from in-person involvement to online affairs. Emotional infidelity, as compared to physical infidelity, can inflict as much, if not more, hurt, pain and suffering. To make matters worse, most infidelity involves both physical and emotional betrayal.