Why does depressing experiences cause people to lose in touch with reality and who they are?

I'm a transfer student and I haven't made any friends. I already been here for pretty much an entire school year. I'm disappointed that I haven't made any friends or got out on any dates. I get jealous of people who have a social life. I'll look at people's facebook and myspace page and they get all these comments, all these friends, and photos having a good time. The sad part is that A LOT of them actually do know or at the some point do know the 300 friends or whatever they have on there. I've heard people say they do know all of those people at some point. All of this loneliness has caused me to become cynical.