Friendships play an important role in individual well-being and romantic relationship satisfaction. While prior research has explored the general benefits of friendships, limited studies have examined how specific types of outside friendships impact couple relationship satisfaction (CRS).

For this study, we define outside friendships as any friendship that involves one romantic partner and a third individual, who may or may not be friends with the other romantic partner. In this study, we examine the influence of different types of outside friendships (individual, family, mutual) on dating and married couples.

Methods

Using a dataset of 934 heterosexual couples (N = 1868 individuals), we analyzed the effects of individual friends, family friends, and mutual friends on CRS. An initial pilot study identified positive and negative behaviors exhibited by romantic partners in interactions with outside friends, which were categorized into six beneficial and five detrimental behaviors. Personal characteristics such as codependency, threat sensitivity, social skills, and personal boundaries were assessed in the main study for their moderating effects. 

Results

Findings indicate that personal boundaries were the strongest predictor of CRS, surpassing even the well-established role of family and friend support. Frequency of negative interactions with individual friends was associated with lower CRS, whereas recognizing the benefits of positive interactions with family and mutual friends enhanced CRS. Dating couples reported higher engagement with outside friends, both positively and negatively, whereas married couples exhibited stronger reliance on family and mutual friends but were more negatively affected by harmful outside friendship interactions.

Implications for Relationships

These findings underscore the complex dynamics of outside friendships in romantic relationships and highlight the importance of personal boundaries and social support in fostering relational satisfaction. Healthy relationships rely on a strong network of friends and families to sustain them, and these networks often change as dating relationships become marriages.