Hi,
I have a similar problem in that i loss all friends, not sure why. but i always used to be so unhappy especially in school years, you know bullying etc... i guess it is a result of that people are so two faced.
at some point i came to the conclusion that everyone only wants to know someone if they are happy, so i started a new life new location etc.. and decided to try and just be happy all the time never saying anything sad or depression and only telling people good things about my life. i also started dancing as a good way of socialising, which helped i found myself with lots of people i was friendly with but realised none of them are real friends. i tried to get know a few better trying to meet outside of the dance situation, put it never really worked out, i found myself becoming paranoid that i would scare them off because i was too clingy or something, then because of something like them not responding to a text felt that they didn't really like me, and these thoughts consume me so much it is horrid, and i think it is that that drives them away.
I started going to church and meet some similar aged people there who are actaully concerned about my problems not just themselves, but i'm so scared of pushing them anway somehow or upsetting them. maybe i anaylise it too much i don't know. having said that i am very happy now, and married with a baby. my husband tries to confince me that people like me he can see i have some kind of friendship parnoia issue.
I don't know if what i have said will help in anyway, but at least you know your not alone in feeling you can't keep friends.