I like you, I really like you
I enjoy being around people. Most everyone has interesting stories, and perspectives I've not had or even thought of. Conversation can be great.
But then, sometimes, not so much.
Confession time: I'm an introvert. Very introverted. Bordering on hermit introverted at times. Two things save me from terminal introversion: an intense curiosity about people and the world, and moderately manic moods.
If I have a defined purpose, I can be be comfortable in nearly any group of people. That is a fortunate remnant of my journalist days. But put me in a group where I'm supposed to just strike up conversations randomly, especially with people I don't know, and I'm promptly in a deep smother. Ack! What do I say? Who do I talk to? How many seconds until I reveal that I am utterly inept and boring? Yeesh. Just toss me out a window now and put us both out of my misery.
Yes, yes, I can randomly strike up conversations without collapsing or hyperventilating. But I'm cringing inside.
I agree that at least part of the reason is social anxiety, the same emotion that causes us to dream ourselves into the most humiliating of circumstances during that extended prone time period known as "rest" or "sleep". Ha! Try to rest while you're just now realizing your skirt hem is tucked into the top of your panty hose just as you walk onto a stage to give a speech. More terrifying than a Stephen King novel!
But another major part of the reason is that I'm introverted. The best definition I've seen for the introversion/extraversion difference is this: Think of your personality as a battery. If you're an introvert, being around people drains you and you need to be alone to recharge. If you're an extravert, being alone drains you and you need to be with people to recharge.
So if I'm visiting you, or we're at a social gathering at the same time, don't take offense if I disappear periodically. I like you, I really like you! But I have to recharge. I even have to do it at my parents' house. I did it growing up, and I do it now. I just go into a room by myself and read, or work on the computer, or - occasionally - stare out the window and think of nothing at all.
When I'm recharged, I'll come out. And no, that's not a threat. It's a promise.