An interpersonal relationship is a relatively long-term association between two or more people. This association may be based on emotions like love and liking, regular business interactions, or some other type of social commitment. Interpersonal relationships take place in a great variety of contexts, such as family, friends, marriage, acquaintances, work, clubs, neighborhoods, and churches. They may be regulated by law, custom, or mutual agreement, and are the basis of social groups and society as a whole. Although humans are fundamentally social creatures, interpersonal relationships are not always healthy. Examples of unhealthy relationships include abusive relationships and codependence.

A relationship is normally viewed as a connection between two individuals, such as a romantic or intimate relationship, or a parent-child relationship. Individuals can also have relationships with groups of people, such as the relation between a pastor and his congregation, an uncle and a family, or a mayor and a town. Finally, groups or even nations may have relations with each other, though this is a much broader domain than that covered under the topic of interpersonal relationships. See such articles as international relations for more information on associations between groups. Most scholarly work on relationships focuses on romantic partners in pairs or dyads. These intimate relationships are, however, only a small subset of interpersonal relationships.

All relationships involve some level of interdependence. People in a relationship tend to influence each other, share their thoughts and feelings, and engage in activities together. Because of this interdependence, anything that changes or impacts one member of the relationship will have some level of impact on the other member. The study of interpersonal relationships involves several branches of social science, including such disciplines as sociology, psychology, anthropology, and social work.

Varieties

Interpersonal relationships include kinship and family relations in which people become associated by genetics or consanguinity. These include such roles as father, mother, son, or daughter. Relationships can also be established by marriage, such as husband, wife, father-in-law, mother-in-law, uncle by marriage, or aunt by marriage. They may be formal long-term relationships recognized by law and formalized through public ceremony, such as marriage or civil union. They may also be informal long-term relationships such as loving relationships or romantic relationships with or without living together. In these cases the "other person" is often called lover, boyfriend, or girlfriend, as distinct from just a male or female friend, or "significant other". If the partners live together, the relationship may resemble marriage, with the parties possibly even called husband and wife. Scottish common law can regard such couples as actual marriages after a period of time. Long-term relationships in other countries can become known as common-law marriages, although they may have no special status in law. The term mistress may refer in a somewhat old-fashioned way to a female lover of an already married or unmarried man. A mistress may have the status of an "official mistress" (in French maîtresse en titre); as exemplified by the career of Madame de Pompadour.