A love triangle describes a situation, typically a rivalry, where two individuals are romantically interested in the same person, or where one person is romantically involved with two separate individuals simultaneously. This narrative device is frequently observed in literature, theater, and film, and statistics suggest it's a common experience in Western society. While formally similar to a friendship triad, romantic love triangles are distinct because romantic love is generally exclusive, unlike friendship.

Historically, love triangles often lead to feelings of betrayal, jealousy, and instability, particularly within monogamous frameworks. One party may feel wronged by the other's pursuit of a third. In some instances, these situations have escalated to violence or suicide. Psychoanalysis has examined love triangles, linking them to Oedipal dynamics and suggesting that patterns of childhood relationships can influence adult romantic entanglements. The concept is distinct from a ménage à trois, which is a consensual three-way relationship, often cohabiting, and driven primarily by sexual desire.

The 'eternal triangle' is often depicted as a dynamic involving a jealous partner (A), an unfaithful partner (B), and a lover (C). In this configuration, A feels abandoned, B is caught between two relationships, and C acts as a catalyst for conflict within the A-B union. Social theorist René Girard explored how envy and mimetic desire can play a role, particularly in situations where men share a bond and a woman enters their dynamic, creating an 'isosceles triangle'. Girard argued that the desired object or person can become a focal point for competition, with the woman sometimes serving as a scapegoat for the rivalry between the men.

When a love triangle leads to the dissolution of a marriage, it can result in a 'defilement taboo,' where the jilted ex-partner demands an end to any friendly contact with the rival. This situation can be particularly hard on children, who may feel torn by divided loyalties and influenced by the 'injured' party's feelings. While stereotypes sometimes assign specific roles based on gender, modern observations suggest that both men and women can equally participate as the 'Other Person' in such dynamics, experiencing comparable levels of passion and folly.

Love triangles are a pervasive theme in various forms of entertainment, including novels, films, opera, and television. Classic literature, such as Shakespeare's 'Romeo and Juliet' and Dumas's works, has long utilized this trope. In contemporary media, particularly young adult fiction and television dramas like soap operas, love triangles are often extended to maintain audience engagement, sometimes spanning decades. Films like 'Gone with the Wind' and 'Titanic' are prominent examples where a central love triangle drives the romantic narrative.