I have the same problem. If my friends ever need anything, I'm there, no questions. Yet none of them seem to feel the same about me. I can't even get a damn email to ask how I'm doing. I always have to come to them.
I decided not to be on Facebook a while back because it was too much of a distraction and was sucking up free time when I needed to be productive in other parts of my life, and my friends all basically act like I fell off the face of the earth and don't exist. I AM the one to text and ask how they are doing. I AM the one to send an email just to say hi or see if they are free for coffee. But no one seems to care what's going on in my life, at all. I'm on an online chat service, but most dont bother to chat at all.
Are we expecting too much? I don't think so. I am a little thin skinned I'll admit, but when friends of 10+ years don't bother to check in and see how life is, is makes you feel pretty worthless to them. I know my worth shouldn't be determined by other people, but when multiple people toss you aside like you're worth so little, well for me, it's hard to think I'm worth being their friend, and I find myself feeling like I'm not good enough for them. I don't really have a family, so my friends are important to me, and so is sustaining those relationships. I've tried just leaving them alone for a while, and no, it doesn't change anything. They still don't keep in touch. I don't have one friend who I could just pick up the phone and talk to and when I've tried, they'll throw in a, "uh, I gotta go..."
It's heartbreaking, to be honest.
I wish I did have a good girlfriend who was always there

Leed is right. Good friends ARE hard to come by. Sigh* I guess we just have to focus on our own lives. Maybe they'll miss us and realize what good friends we are. Maybe not :\