From the Institute for Family Studies:

For over a decade, happiness has been in free fall among young adults. The share of young adults ages 22 to 35 who reported being “pretty” to “very” happy has fallen by 12-percentage points since 2010. Notably, these declines in happiness have been concentrated among the unmarried. From 2010 to 2024, happiness among married young adults fell from 94% to 90%, compared to a decline from 82% to 68% among unmarried young adults, resulting in a 22-percentage point gap between the groups. This growing marriage-advantage may be driven by both selection effects into marriage and marriage’s protective effects against isolation in a digital age.