open relationship

An open relationship is an interpersonal relationship in which the parties want to be together but agree to a form of a  non-monogamous  relationship. This means that they agree that a romantic or intimate relationship with another person is accepted, permitted, or tolerated. Generally, an open relationship is when the parties involved have two or more romantic or sexual relationships occurring at the same time either as a short-term relationship, such as dating, or a long-term relationship, such as marriage. The concept of an open relationship has been recognized since the 1970s.