(((HUGS)))
Wish I had an great answer for you..but honestly I don't really know... I don't know all the specifics so I don't don't know exactly where or why this stems from.. from my own experiences I can speak maybe something will stand out to you.
I have social anxieties and fear rejection and there have been many long episodes of depression and isolation as well. Social anxiety and fear for me comes from a lifetime of feeling like I just don't fit anywhere. Never was really comfortable out and about around people. I guess it is kinda a snowball effect but I don't remember ever feeling more comfortable in social settings but know over the years I have pretty much stopped trying to push myself as well.
I do know I'm much happier with one on one interactions. Also that I only really like being around certain people. They have come and gone and I am not good with keeping up contact. All the people I have considered friends have been very different in regards to personalities, interests, and rather random in general. The only thing really in common was the level of ease I felt around them.... I know why I don't like group settings tho. I don't like how people act in groups. And the conversation is generally boring, basic or inside jokes amongst the group and since I never really sought out a group but had friends/acquaintances in many different groups. I would end up in group settings randomly and always felt like the outsider. And I would end up being bored an just zoning out and nodding or whatever a lot. Or I would be nervous and awkward and try to interject/ jump into conversation always saying the wrong thing or at the wrong time or being overlooked gone unheard. Sometimes get repeaty..just generally becoming more and more awkward and frustrated and embarassed. So I think going blank and zoning out became the norm. So the whole thing became an exhausting dreadful boring chore. And just stopped wanting to even push myself to go out at all. Staying in wearing pj's watching TV seemed like a much more enjoyable experience...for a bit until I would feel lonely and bored and then try to find someone who was available to hang out, wanted to, or hadn't lost contact with all together. Sometimes no one would answer their phone or they were going out with people who I had no interest hanging out with and/or didn't lie hanging out with me either. ..so just depressing and limiting... Honestly, I think the best times I've had with friends were not planned at all. More like when out at apps / errands or in transit to r from work or whatever and random run into someone and it just so happens we both had time to do whatever. That's all I can really think of...Idk...maybe some of us are just kinda lone wolves...wandering souls...that find the whole rigamaru of social/societal structure /expecations to be absurd. I guess what is normal to most seems ridiculously unnatural to me and others I'm sure as well.. Don't thrive in capitivity I guess. So, yes I can be feel lonely alot, and it is nicer when I did not live alone...but as far as outside in the world interacting I'd rather have a random great time with someone I happen to cross paths with than try to force myself to make/accept plans and have a miserable time pretending to be someone I'm just not. I hope something I said was helpful
Be Well! Be You! and Keep Writing! -LITW