Source: Subreddit Stats

The Signal: While monogamy remains by far the most common relationship arrangement in the US, consensual non-monogamy (CNM) is slowly becoming more mainstream as 4-5% of American adults (~8-10m people) currently practice CNM in some form. Perhaps more surprising is that 20%+ of surveyed single adults have participated in CNM at some stage in their lives. 

The Big Picture: Alternative lifestyles are becoming mainstream.