A relationship breakup, breakup, or break-up is the termination of a relationship. The act is commonly termed "dumping [someone]" in slang when it is initiated by one partner. The term is less likely to be applied to a married couple, where a breakup is typically called a separation or divorce. When a couple engaged to be married breaks up, it is typically called a "broken engagement". People commonly think of breakups in a romantic aspect, however, there are also non-romantic and platonic breakups, and this type of relationship dissolution is usually caused by failure to maintain a friendship.

Susie Orbach (1992) has argued that the dissolution of dating and cohabiting relationships can be as painful as or more painful than divorce because these nonmarital relationships are less socially recognized.

Kamiar-K. Rueckert argues with the works of Donald Winnicott that the ability to be alone is an essentially healthy sign of emotional development and maturity. Once a child has obtained closeness and attachment by their early caregivers, they are able to develop autonomy and identity. If children have not introjected the good and protective qualities of their parents, they will fear separation and break-ups.