What is self-expansion in relationships?

Self-expansion in relationships refers to the idea that individuals enter relationships to enhance their sense of self and increase self-efficacy. It's a concept that was originally developed by Aron and Aron in 1986. According to the self-expansion model, people are motivated to form relationships because they make us feel good about ourselves and more capable. This metric of self-expansion considers one's perception of oneself as seen through the relationship with another person. This feeling of enhancement is particularly strong at the beginning of relationships, when forming pair bonds and is linked with autonomic nervous system functions like pleasure, arousal, and excitement 1.

In a study cited by Andrew Huberman, couples were evaluated on their levels of self-expansion, which affects how they perceive the attractiveness of others outside the relationship. When individuals experience self-expansion, such as hearing their significant others say great things about the relationship or about themselves, they tend to find alternative partners less attractive. The study found that narratives focusing on the relationship being exciting, novel, and challenging, or expressing strong feelings of love previously experienced, led to lower brain activity associated with assessing the attractiveness of others. Thus, individuals who benefit from self-expansion and feel "filled up" by the relationship tends to view outside options as less attractive 2.

The implications are that self-expansion can shape our perception of potential partners and impact the stability of romantic relationships. It is crucial to have a stable internal representation of oneself and a stable autonomic nervous system to establish desire, love, and attachment within a relationship. Otherwise, if one's sense of self-expansion is too dependent on another person, they might become susceptible to the attractiveness of alternative partners, adding instability to the relationship 3.