My take is to review prior abandonment. Very few people in your life will have a relationship that's both strong and life-long. (As a very significant footnote, I am not going to justify abondonment by close family or disrespectful/exclusionary acts by friends, only more "natural" separations). It's very easy to lose people as you change homes, schools, jobs, and hobbies. For a long time, I felt that was all due to them being fair-weathered and abondoning me, you could say. Maybe I wasn't great, either. But, as circles have come and gone, I've learned to stop feeling sad for the friends I've lost and instead enjoying both the friends I currently have and the times with friends of the past. That in no way is meant to say the prior friends are thrown away, but rather it is to say live in the moment and cherish the memories.

I miss my best friend from pre-school, but we no longer live across the street from each other. I miss my best friend from 2nd grade, but we no longer walk to school together. I miss by friend circle from 6th grade, but I no longer go to their church. I miss my friend circle from high school, but I no longer play soccer with them. I miss my friends from college, but we no longer dorm together. I miss my friends from every prior job, but we no longer spend 40 hours a week together. I miss my biking friends, but it's winter. I miss my cousins, but we've moved apart and rehashed who our closest family members are by way of our spouses. I have my current work friends, I have my current hobby friends, but they, too, will likely be inactive parts of my past at some point. Every friend listed here was a friend not just from compatible personalities, but also from shared experiences. For a long time, I mourned their absence and felt everything was superficial. But, quite frankly, that's just not right. I do not regret any of the fun times spent with them. They were friends that day. You might see them again.

Stop putting asterisks on your acquaintances to degrade their status. Maybe it's less abondonment and more natural separation.

This comic chart has stuck with me since I first saw it. I believe it helped me understand this sort of zen mindset. It is by Olivia de Recat, though it appears her original site is down. What stood out to me is that the lines are not defined as "me vs them". They're ambiguous. Either line can be the first to depart. Either line can be the first to return. The FWB one shows how a slow departure can trigger the other to simply leave entirely, a pattern likely present in many former relationships of any kind. Neither person is in full control. I've pictured many other paths since then.

Practice.

Surround yourself with people, when one of them clicks more, let then in your inner circle little by little.

I would recommend starting by joining a group around a topic you’re interested in. Local climbing club or anime group or sports enthusiasts or gaming clan or whatever. Something in person. Use that group to practice social skills and learn body cues with topics you’re already familiar and confident with, and that in turn will help you branch out to other topics when you’re ready with the same level of communication.

It is a learned skill, and it takes time, but if you never take the time to learn it, then it will always feel foreign to you. Does that make sense? Like so many things in life, you have to get past the fear to get to the reward. That can be difficult, and you might get hurt when you put yourself out there, but I believe if you keep with it, and you’re determined to make a change, you can absolutely overcome anything and find a social group that complements you.

Good luck, friend. You can do it. We believe in you.

Basically aversion therapy. You have to force yourself to until it gets easier.