So, at the beginning of last semester, I broke up with my girlfriend at the time and have been completely obsessed with her since then. I didn't even like her as a person to begin with, but whenever I hear about her hitting on my friends, I start going batshit inside my head. Even without that, I find myself checking her facebook constantly (I defriended her like 5 minutes after breaking up) at least once or twice a day. I run through the relationship and think about her at least a few times every hour. I hate being this fragile. If I see her or hear about her, I'm totally ruined for a few minutes after that.
The thing is, she isn't special. I do this with all people I get really close to and then have a falling out with. The closest thing that comes to this is when my best friend in HS (years ago for me, haha) decided to stop talking to me for 6 months because we had a major falling out. I would think about that f****r constantly and I wasn't even gay, haha.
I also have this pattern of getting completely obsessed and engrossed by my non-people related interests in life. Often these obsessions are healthy ones (guitar/music, photography, science, brains, and language). There can only be one existing at any one time, though.