This study examined how attachment styles differ across relationships for romantic partners, same-sex friends, and cross-sex friends. It found that for individuals in a romantic relationship, attachment scores for romantic partners were more similar to primary caregivers, while scores for same-sex friends were less similar. For single individuals, attachment scores for cross-sex friends were less similar to caregivers. The study suggests romantic partners can influence attachment styles for other relationships, acting as a proxy for the primary caregiver attachment. However, early caregiver attachment remains stable over time.