Ok, can someone tell me what would cause someone to act like this...?

I tried putting this in Singles&Dating but I don't think it was the right place.. Anyway, I could be completely infatuated with someone, for whatever amount of time, until it's mutual, and if we end up together or in a relationship, I then completely reject them, don't want them anymore... What... show more I tried putting this in Singles&Dating but I don't think it was the right place.. Anyway,
I could be completely infatuated with someone, for whatever amount of time, until it's mutual, and if we end up together or in a relationship, I then completely reject them, don't want them anymore...

What is/causes this and how do I stop doing it?
Thanks a lot...
Update: Thanks rckts!
9 answers 9