Agapé is a light-touch relationship enhancement smartphone app. This study used data from a longitudinal study couples using the Agapé app to link change in an array of behavioral processes into mechanistic chains, thereby providing some of the first quantitative insights into how various relationship processes might be linked as they shape the course of relationships. A sample of 405 couples in long-term relationships (810 partners, 50% women, 75% white, together M=4.5yrs, 50% living together, 33% currently dissatisfied) completed assessments across their first month of using Agapé. Men and women significantly improved on 15 of the 16 relationship processes assessed. Network analyses highlighted increases on three processes (quality time spent together, perceived partner responsiveness, and gratitude toward partner) as the processes most proximally linked to increases in relationship quality. The network findings also uncovered a number of indirect mechanistic pathways to be explored in future studies (e.g., increases in couples talking about their relationships to increases in awareness within those relationships to increases in gratitude and quality time to increases in relationship quality). Thus, the results offer a tentative blueprint for the inner workings of relationship dynamics and guidance toward optimizing the benefits of Agapé.