1. the tendency of relationship partners to think of themselves as members of a dyadic relationship rather than as distinct individuals. As close relationships, particularly romantic ones, develop over time, partners display increasing levels of mutuality, which may influence their affect, cognition, and behavior. For example, when mutuality is high, people tend to think of their partners’ characteristics and resources as their own.

2. in interdependence theory, the tendency of partners to depend equally on each others’ behavior for the attainment of desirable outcomes. In asymmetric relationships, one partner plays a larger role than the other in determining what outcomes each partner receives, but in relationships characterized by mutuality, their power and influence are approximately equivalent.