Adolescence and emerging adulthood are both stages in which romantic relationships play a key role in development and can be a source of both well-being and negative outcomes. However, the limited number of studies prior to adulthood, along with the multiplicity of variables involved in the romantic context and the considerable ambiguity surrounding the construct of well-being, make it difficult to reach conclusions about the relationship between the two phenomena. This systematic review synthesizes the results produced into this topic over the last three decades. A total of 112 studies were included, following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) guidelines. On the one hand, these works revealed the terminological heterogeneity in research on well-being and the way the absence of symptoms of illness are commonly used to measure it, while on the other hand, they also showed that romantic relationships can be an important source of well-being for both adolescents and emerging adults. The findings underline the importance of providing a better definition of well-being, as well as to attribute greater value to the significance of romantic relationships. Devoting greater empirical, educational, and community efforts to romantic development in the stages leading up to adulthood are considered necessary actions in promoting the well-being of young people.