Same reason most of us are. Deep down there is something wrong with all of us. Some of us hide it better the rest of us, but we are all fucked in the head. Being alone isn't so bad. As long as you occasionally have someone to natter with in IMs and lots of things to keep you busy, it's almost like living. I make masks, dozens of them. I hand them out to my nieces and nephews to share with their friends, and each one gets a little better then the last. When I need human contact I can try and call a family member to come visit, or if they are busy the Catholic Community Relief Services is always happy to see me come in and donate a few hour to helping them out with what ever is going on. Night time is the worst though. When no one is online and you are tired of reading the same shit books, and TV just disgusts you with it's chattering heads. Your mind starts to move at weird angles and you just want someone there that you can hold so you know you are real that you matter and that at least one person gives a fuck whether you are there tomorrow.
So yeah, nights are rough. I find doing as many pushups as you are physically capable of helps.
Basically relationships are doomed to fail, they aren't worth the drama, and opening yourself up to be hurt again and again only makes you hate the world. No matter how much you try to make it work because you are fucked in the head it will fall apart and leave you even more fucked in the head then before.