I'm not sure I'd describe myself as a loner, but I definitely don't seem to need to stay as in touch with people as some other people might. When I first moved to Red State, I did everything I could to keep in touch with people I left behind -- snail mail, emails, phone calls, IMs -- and after a while, despite my efforts, those interactions started to dwindle. It's just a fact of life -- when you don't see someone regularly, when you're working, starting a family, etc., you get busy and your priorities change. It's not that you don't care, it's just that there isn't time enough in the day to keep track of everything you want to do.
The people I talk to most on a weekly basis are my mother, Florida Girl and Rocky. My brother and V would round out the top five. Of those five, the only ones I talk to on the phone more than once a week are my mother and Florida Girl. I IM and email Rocky regularly, email my brother a few times a week, and the same goes for V (though I usually do talk to V on the phone at least once a week if we don't have a dinner or coffee planned). Other than that, I'm pretty fine with dealing with people on a semi-regular basis and it takes a while before I realize, "Oh, wait, I haven't talked to so-and-so in a while." Or I'll put off answering an email because I got home late, and I'm running around trying to get stuff done and before I know it, weeks have gone by and the email is still in my inbox unanswered.
I tend to be wary as well, and don't move quickly to incorporate people into my life.
And even once someone is in my life, my attachment to that person isn't as strong as it would be to say my mother and brother (for obvious reasons) and Florida Girl (my best friend since college) and Rocky -- my partner-in-crime. The strength of these relationships have developed over time, spanning many years (I think I've known Rocky for more than five years now, and V and I became friends in grad school -- which is an accelerating process).
I'm really leading up to a question, I guess, of some sort. How often is normal to talk to people if you're friends? In general, I don't talk to the vast majority of my friends more than a couple times a month (granted many live out of state, but then again, Florida Girl and I can speak as often as 5 or 6 times a day, depending on Stuff (tm)). I recently saw a friend of mine who lives here in town for the first time in six months; we'd probably exchanged maybe three phone calls in that entire period and that was fine. If I didn't hear from a friend for a while, and assuming I knew everything was okay, I probably wouldn't think too much of it. But I think that's where I diverge -- does friendship mean constant, prompt communications? I'm truly baffled, so if anyone has any insight into this, I'd love to hear it.