Addiction is a psychological and/or physical dependence on substances, activities, or behaviors. Tolerance increase, difficulty in interrupting or reducing the investment in the relationship, and frequent concern with it are possible symptoms of a love disorder, a behavior addiction in romantic relationships. However, this pathology is not an official diagnosis, and literature about this theme is scarce. In this manner, the present study aimed to characterize love disorder s nomological and nosological nets. For that, two studies were conducted. An online questionnaire composed of sociodemographic questions and a battery of scales was answered by 1,310 adults, with a mean age of 30.3 years (SD = 12.2). In the first study, satisfactory evidence of validity was found for the Love Addiction Inventory - Brazil, based on the internal structure, and in the relationships with other variables, such as self-esteem and convergent instruments. In the second study, the nomological and nosological nets of love disorder were investigated, and relations between love addiction, emotional dependence, pathological love, attachment, passion, personality, relationship satisfaction, and stress were explored. It was found that the love disorder nomological net is constituted of a positive relation with stress and a negative relation with relationship satisfaction. Data points out the love disorder as a distinct pathology from passion that can be partially explained by attachment-related anxiety and personality characteristics. These findings are relevant to clinical diagnosis and future intervention research.