Relationship infidelities are motivated by many distinct factors, with previous research indicating motivations of dissatisfaction, neglect, anger, and sexual desire (Barta & Kiene, 2005). We expand on this by demonstrating additional, empirically distinct motivations for infidelity. Using an Internet-based questionnaire, participants (N = 495), most of whom were young adults, self-reported their ... [Show full abstract] infidelities. In addition to evidence for previously studied motivations, our data demonstrate additional factors, including lack of love (“I had ‘fallen out of love with’ my primary partner”), low commitment (“I was not very committed to my primary partner”), esteem (“I wanted to enhance my popularity”), gaining sexual variety (“I wanted a greater variety of sexual partners”), and situational factors (“I was drunk and not thinking clearly”). Our results also show personality correlates with infidelity motivations. Consistent with predictions, attachment insecurity was associated with motivations of anger, lack of love, neglect, low commitment, and esteem, while unrestricted sociosexual orientation was associated with sexual variety. Implicit beliefs (e.g., growth, destiny, romanticism) were differentially associated with sexual desire, low commitment, lack of love, and neglect. These findings highlight multifaceted motivations underlying infidelity, moving beyond relationship deficit models of infidelity, with implications for research and psychotherapy involving people’s romantic and sexual relationships.