It's possible that you've outgrown them. I don't think there's anything wrong with that either. I've grown apart from plenty of people over the years because we grew into different people. It's natural. I think solitude can be a great thing but it's possible to get too much of it. I was alone a lot for the better part of two years and it took me a while to get comfortable with being around people again. I swear that's when my social anxiety first kicked in.