We’ve already established that romantic relationships are a universal desire, and additional research shows that individuals across cultures value a variety of relationships similarly (Endo, Heine, & Lehman, 2000; Landsford, Antonucci, Akiyama, & Takahashi, 2005). The reasons for forming specific relationships, however, are as individual and complex as each of us and rooted in unique needs and motivations, which may develop and change over time. In this section, we examine the factors of relationship formation, including proximity, attractive qualities, similarity, and personal and social needs.