I think it's partly also that a lot of people's 20s go at different speeds. Like, I was married at 24 and had a first kid at 25, so that put me on kind of a dif

I think it's partly also that a lot of people's 20s go at different speeds. Like, I was married at 24 and had a first kid at 25, so that put me on kind of a different track from people I knew in university and high school who started their families 3, 5, even 10 years later than that. Yes, I'm now 39 and have indeed reconnected with some of those people, especially as they've started to "catch up" and we have contemporary experiences in common again, but basically it's really hard as a parent of young children to keep up with the social expectations of unattached or childless people; you just can't drop everything for that last minute beach day or road trip, and if you do make the extra lift so that it can happen, you can still end up feeling like you're holding back potential further spontaneity, if it's with a group where no one else really "gets it". The instinct is to gravitate toward socializing with other people/families who are in a similar life stage.