when I was 13 we moved to Los angeles, I didnt know anyone, in a fairly small school, had to make all new friends, learn to socialize again, still kept in touch with israeli long term friends (we visited once a year at least), but no one from kansas. Slowly gathering friends here. then right at the end of highschool I realized a lot of people were just circumstantial friends. Social awkwardness caught up with me, folks I thought liked me were just there because of proximity.
Didnt know the college system well enough so went into a local community college, made some interesting friends, kept a couple from highschool kept in touch kept doing things together but mostly slowly rebuilt my "group" eventually figured out I love animation and art, applied to a real art school, and lost touch with all my community college friends..
in college again I built a group, small, I would socialize get close to, but eventually graduated, and lost touch, by graduation I had 2-3 close people but between pickiness and awkwardness I lost mostly everyone again.
as a graduate again worked hard, used okcupid, used meetup made a nice group of friends! ... 3-4 years later people grow apart until a big event happens and everyone breaks off on their own...
working a real job now and this cycle has repeated... maybe 2-3 more times making, keeping friends is a part time job, organize social events check in on people, assume there's always going to be a turnover, I still have friends I knew when I was 5 years old but we talk... rarely (though comfortably when I visit israel) and you simply cant stop life from eroding at that.
to not be alone, at least in the current world, I feel like I have to constantly make NEW friends, find new activities put myself out there, I've met people through dating apps, roomate situations, second hand connections, love interests, I'm NOT the most socially capable person but I keep hitting my head against that lonliness wall and at this point there's a nice deep dent in it to remind me it's not futile.