In my teens and early twenties, I avoided parties and large social gatherings, but would go out and do things, including going to concerts and movies (albeit alone). When my friends were around, I was pretty unwavering in what I would and would not do. If I knew it would make me uncomfortable, I'd stay home or do something else while they did the other thing.
Since my middle twenties, with less reason to go out and do things, I've felt more and more isolated and lonely, but content, as I dislike the alternative. I enjoy interacting with people online, and to a limited degree in person, but as for the latter, the opportunity does not arise as much. I don't know if I am getting worse, or it is a side effect of getting older. Either way, I guess I would say I'm more isolated than I've been in the past.