I definitely consider myself an introvert. I can talk, talk, talk all day long, deal with crazy people, deal with strange phone calls, and chit-chatty clients. I go out with my friends, and out to dinner, and have conversations with the guy who makes my coffee at Dunkin Donuts.
But, at the end of the day, when all that is over, that's when I like to have the peace and quiet of my own space to relax.
Wanting to live alone has nothing to do with wanting to avoid people, with being anti-social, or anything like that. For me, being introvert means I need my space to relax and rest, and NOT have to talk to anyone after talking all day, and I can't do that as well with roommates. Personally, I think intro/extrovert has nothing to do with daylight hours--its just a matter of how you wind down at the end of the day!