I had two guys I maintained good friendships with after college, and then eventually they moved away, and we drifted apart. I did see one of them a few years ag

I had two guys I maintained good friendships with after college, and then eventually they moved away, and we drifted apart. I did see one of them a few years ago, but other than that I haven't. I had much better luck meeting people that have stuck around via going to Meetups regularly. Sure, quite a few people I met through Meetup eventually drifted apart, but I still keep in touch and hang out semi-regularly with about 20 people (almost all I first met eight years ago). Most of us like to play board games, so a lot of these are board game gatherings. Also these gatherings aren't organized through Meetup anymore, we're all just friends now. I also still do things with a local writer's group from time to time, and several of those people I've known for over a decade now. Finally I have some game designer friends (got up to 8 people at one point, but a couple people moved away) that I've been meeting up with several times a year (except during the pandemic, although we have started meeting up again recently) for the past four years. That started by me just going to game designer conventions and going "Where you from? Oh you're from near me? I host a playtest night roughly once a month, you should come." So basically all these boil down to having some sort of shared passion. Those have helped maintain those friendships. You can always just invite someone to something related to the passion, although it doesn't have to be limited to just that. Most of these didn't happen until I was long out of college, btw. Most of my 20s were pretty lonely outside of work until I started going to these things.