I'm really late to this thread, so I am going back to your OP - part of what you said is a problem I struggle with also: I want more friends or better friendships, but when it comes down to how I want to spend my time, I'd often rather be alone.

I've done very little thinking about why this is as I am not sure it would help, but I have tried the 'talk to people more' approach. I find that it has made talking to people easier, but I am not sure that I like it anymore than I did before. I feel like I need to do it in order to advance professionally, but at the same time, I never feel quite good enough to decisively move forward. I am reluctant to reveal much about myself or projects I work on because I feel like a fraud, like I don't know enough.

I'm kind of scared to get too introspective or deep about all the whys, but I also have that conflict of want/don't want.