Throughout life people form multiple close connections. These connections play an important role, such as providing social and instrumental support. Despite this, relatively little is known about how and why closeness to multiple others changes over time. To fill this gap, we examined changes in perceived closeness to multiple social connections and used a well-studied relational individual difference—attachment style—to shed light on those changes. Multilevel analysis and different indexes revealed that attachment avoidance was associated with lower mean perceived closeness and greater fluctuations in perceived closeness over time. These associations were moderated by attachment anxiety, such that low levels of avoidance and anxiety (i.e., security) were associated with greater stability of perceived closeness. Our results demonstrate that perceived closeness in one’s social connections tend to change, even over relatively short periods of time, and individual differences such as attachment style are important correlates of these changes.