Might be depression; sounds like some of the symptoms, and suddenly being alone and adrift might cause it.
Here's a google search link that'll turn up a number of sites that talk about the symptoms of depression. Take a look at a few and see if any of it applies:
http://www.google.com/search?hl=en&i...=Google+Search
Aside from anything else, keeping busy is one of the best ways to fight depression. Try to get some of your old friends back. You may have a problem with overdependency on women, (or obsession, who knows?) especially if you dump friends every time you get a new girlfriend. And maybe you should look at that. But the key thing now is to get busy with something and hang out with people. Maybe lay off women for a while until you haev a better idea of why you do what you do.