I had one best friend at school but was always on the fringes of friendship groups. At university (nursing) the culture was clubbing and drinking a lot which I wasn't interested in. I liked meals out, going to museums and galleries and reading. So although my roommates liked and accepted me, I was still on the fringes. Groups generally freak me out. I get very nervous and my mind goes blank.
I've always been a floating friend, not anyone's priority and certainly not someone to come running for if the worst happens.
I never became a nurse (dropped out) but in every job since I have got along people just fine, but I am not one for making great strides in being friends. I am a lousy friend anyway. I cancel at the last minute, I ghost people, and I am a lazy person. I would rather be alone with my books, or with art, or in an English Heritage property!
About two years ago I had an episode of depression and out of that came a long period of anxiety. Lots of things were happening at once at the time but because of my lack of social circle I thought I had to deal with it alone. I found common ground with a couple of colleagues who were going through the same thing, and a couple more stepped up to help, but out of all of them I am still only really friendly with one of them. She seems genuinely interested in being my friend so we'll see how that goes.
I have had counselling and decided that I'm an introvert, with a bit of social anxiety thrown in. Extroverts don't understand why I have lousy eye contact and why I'm so quiet. I watch people a lot and think a lot, but I don't talk a lot. Extroverts sometimes think I'm rude. Not my intention, but I understand their reasoning.
I recently disengaged from another friend after he stopped contact. 20 years ago I would have gone a bit mad but now, although I miss him, I think it just falls within my pattern. I don't expect the other friend to stick around either but I might be surprised. I have to make the effort.
It used to be a problem for me but I'm now in my early 40s and I think it's just me being me.