Open marriage is a form of non-monogamy which views extramarital sexual engagements as moral. The partners agree that that their relationship is not socially or sexually exclusive. It is unique for every couple as it may or may not involve one-night stands, friendships, contraceptives, and other arrangements. This type of relationship may be difficult because of varying expectations and varying levels of emotional attachment. This kind of agreement is generally illegal in jurisdictions which view adultery as illegal even if the partners involved have given their consent.