“A Pew Research Center report published in 2021 found that the share of American adults ages 25 to 54 who are married fell by almost 15 percentage points between 1990 and 2019, from 67 percent to 53 percent. The rising share of unmarried people living with a partner accounted for a bit of that drop, but it was mostly driven by people living without a spouse or partner. In 1990, adults were more than twice as likely to be married than on their own, but by 2019, the gap between the two groups had narrowed considerably.”
https://fivethirtyeight.com/videos/who-is-nikki-haley-trumps-first-major-challenger/