The answer is sort of obvious but, doing it will likely be really difficult. You obviously need to be in situations where you are around people and it's acceptable to talk to them. I always considered joining a rambling club but, anything really- where groups of people gather to do things they have an interest in. Lecture series, sports clubs, evening courses, coach trips, social clubs, whatever.
I struggle too with social anxiety/ introversion/ embarassment in social settings. Ultimately, it was a choice for me. Did I face my fears and try to build friendships/ talk to people- with the possible benefit that it could make me feel better or, did I shy away. I ultimately chose to shy away because I actually enjoy being alone and I'm lucky in that I don't tend to feel lonely.
If introversion feels too much to get over- then I guess you have to put work in to tackle that. I imagine there are therapists who focus on it. I also considered trying to tackle my social anxiety. Maybe assertiveness training or something. Mine was more career related though. As it panned out, I was able to dodge the bullet and work alone. But, it's absolutely held me back in life.
I think you have to decide just how upsetting it is to be alone and how much you want to change. I feel like it must be possible but I imagine the path to it will be difficult and uncomfortable. I think it just becomes- what can we live with easier?
