That wasn't exactly what I was implying - more that it's now more socially acceptable to spend your teens and twenties focusing on things other than finding a partner and getting ready to have kids. I know plenty of people who did get married in their 20s, or at least had a stable relationship, but also a good number of people who were focused on their career or hobbies instead and maybe dated occasionally.

I'd actually be curious what the median age people get married at is now vs. in the 80s, although I'd assume that's confounded by people who just don't get married but are functionally in a similar level of committed relationship.

My overall point is that if you're 35 and single now, you're less of a social pariah and automatically seen as a failure of a person. You're also probably experiencing less social or familial pressure to "just settle down with someone". People are having sex and in relationships more because they want to than because they're pressured to.