The landscape of modern marriage is undergoing a profound structural transformation. Traditional marital expectations are increasingly giving way to flexible configurations, moving consensual non-monogamy (CNM) from a niche subculture into mainstream sociological discourse. Are open relationships truly gaining widespread acceptance, or do they still face rigid societal resistance? Backed by authoritative institutional research and legal milestones from 2025 and 2026, this article delivers a clear, data-driven analysis of the numbers, boundaries, and realities defining open marriages today. Key Open Marriage…