Mental health research, psychiatric practice and neuroscience have long oscillated between individual-centred and socially embedded paradigms. After the rise of social psychiatry in the mid-20th century, the field largely turned toward individualized, biological approaches. However, growing calls across neuroscience, psychiatry and psychotherapy now signal a renewed focus on relational processes. Recent theoretical and empirical developments suggest that psychiatric disorders may be better understood as disorders of social interaction rather than isolated deficits. Concepts such as interpersonal misattunement, interaction-based phenotyping, and second-person neuropsychiatry offer promising alternatives to traditional observer-based models. Alongside these ideas, the emerging field of relational neuroscience, using methods such as hyperscanning, provides tools to explore the dynamics of reciprocal human interaction. Multi-person approaches also offer potential for advancing our understanding of psychotherapy and other relational settings by moving beyond isolated individuals to the dynamics of shared experience. By capturing meaningful interpersonal moments as they unfold, these approaches may offer insights into the neurobiology of relational change. We propose that a more comprehensive understanding of moments of genuine connection holds promise for advancing mental health research and supports new forms of relationally attuned mental health systems.