Breakthroughs in understanding addiction and close relationships

•Substance use can either be a source of pleasure or strain for close relationships.•We discuss support for substance use on relationship quality and conflict.•We discuss support for relationship functioning on subsequent substance use.•We identify moderators that buffer or exacerbate these associations.

Substance use is one aspect of life that can serve to bring couples together or tear them apart. Evidence has accumulated for both substance use affecting relationship distress (e.g., partners of substance users report poorer individual and relational outcomes) as well as relationship conflict affecting subsequent substance use (e.g., individuals use substances as a way to cope with interpersonal conflict and distress). We discuss several determinants of each association, including individual difference and relationship-specific constructs. We conclude by considering how conceptualizing addiction as an interdependent — rather than independent — process is critical for future theory refinement and intervention development.