Shouldn't the breakup make you feel better? I mean, if she was bad to you, you should feel relieved that it's over now.
Just speculating, but there could be emotional abuse. If she would be bipolar, and lead you on trying to be all like "I want to be with you forever and you are the best person ever" and then it dies down and then she hardly speaks to you for a week. You might just be left with the impression that good times will come back. Likewise, if something like that lasted, op would be fooled into thinking that he just gave up the good stuff.