This study aimed to identify and conceptualize the social implications of family sustainability within the socio-cultural context of Isfahan and to develop a grounded theoretical model of this phenomenon. A qualitative research design was employed using the systematic grounded theory approach. The fieldwork was conducted in Isfahan with 14 family specialists and experts selected through purposive–theoretical sampling. Data were collected via semi-structured in-depth interviews and analyzed through open, axial, and selective coding. MAXQDA software (version 2022) supported data organization and visualization. Credibility was ensured by member checking and external expert auditing of codes and interpretations. Analysis revealed that family sustainability is a multidimensional construct conceptualized as “family sustainability as future-oriented interactive–institutional cohesion.” Causal conditions included anomic socialization and couples’ social capital, while contextual conditions comprised family support and fragmented interaction. Intervening conditions such as dysfunctional interaction patterns and the structural pull of social media influenced the dynamic process. Key strategies enhancing family sustainability involved redefining the social system around family-centered policies and promoting rational partner selection. The ultimate outcome was “social system coherence,” manifested in improved societal integration, security, and collective stability. The findings indicate that sustaining families extends beyond internal dynamics and requires addressing broader socio-cultural and communicative structures. Strengthening couples’ social capital, reorienting social policies toward family centrality, and managing the influence of social media are essential to achieving resilient and cohesive families that contribute to overall social order and well-being.