Self-Expansion Model: How Relationships Grow (and Stagnate) Us

Evidence-based practices for sustaining closeness and personal growth through the self-expansion mechanism

Why do close relationships feel exciting at first and how do you sustain that over time?

Arthur Aron’s self-expansion model proposes that people are motivated to grow — to expand their sense of self by incorporating new perspectives, skills, and resources — and that relationships are so motivating early on because they represent rapid self-expansion. The well-studied practical implication is that doing novel, challenging activities with a partner or close friend restores the expansion experience and revitalises closeness. The model has a substantial empirical base, primarily in romantic relationships.

Arthur Aron and colleagues proposed that humans have a fundamental motivation to expand the self — to grow more capable, knowledgeable, and connected. Relationships are initially exhilarating because they are the fastest route to self-expansion: a new person brings perspectives, experiences, and capabilities you did not have. When the novelty ends, expansion stalls — and the relationship can feel stagnant not because affection decreased but because growth stopped. The practices below are grounded in Aron’s published research programme, with honest notes on what the evidence directly supports.