Unrequited love is the love felt by one person towards another but is not reciprocated. Several typologies have been developed, however studies often do not distinguish between differing relationships (e.g., strangers, acquaintances, friends). Unrequited love relationships are less emotionally intense than equal-love relationships. If one falls upward (falls in love with someone with higher mate appeal), that person is not likely to reciprocate one’s love and that love will be unrequited. In addition, unrequited love can be a ‘false start’ on the path to a mutual-love relationship. Research suggests that the pursuer/rejected and the target/rejecter of unrequited love have substantially different perspectives on the situation. Pursuers look back on the episode with both positive and intensely negative emotions, whereas rejecters are more uniformly negative in their accounts. Rejectors and rejected persons also differ in their guilt, self-esteem, and perceptions of persistence. Some dyads can maintain a friendship after the rejection, depending of variables such as prior commitment and current friendship maintenance behaviours. Unfortunately, unrequited love sometimes leads rejected pursuers to engage in negative relationship behaviours, including stalking-related behaviours.