Intimate relationships among contemporary emerging adults frequently manifest as situationships, characterized by emotional closeness in the absence of explicit commitment. Shaped by digital culture and evolving social norms, these relationships reflect heightened uncertainty and psychological tension within modern intimacy. The present study conceptualizes situationship as a multidimensional psychological construct, including commitment ambiguity, avoidance of emotional investment, and anxiety related to relationship uncertainty. Associations with attachment anxiety, trust, and subjective well-being are also investigated.To examine these dynamics, an integrated scale development and validation methodology was employed. The results indicated a stable three-factor structure. Structural equation modeling demonstrated that experiences of situationships were positively associated with attachment anxiety and psychological distress, and negatively associated with trust and well-being. Importantly, attachment anxiety partially mediated the relationship between relational ambiguity and relationship-related well-being.These findings establish relational ambiguity as a measurable psychological construct. The study contributes to positive psychology by enhancing understanding of relationship health and emotional regulation within contemporary intimate contexts. The results suggest that interventions promoting commitment clarity and emotional openness may enhance psychological well-being in emerging forms of intimate relationships.