Why do we keep going back to someone who hurts us?

we had really problems and many times came back together, but when people do something that you dont like its just terrible feelings and always is the same.
i think that when you are coming back many times you have emotional addiction and always waiting to go again back maybe in some time.
its really hard, he wants to be friends, I really like his as a person he is really good person just not for me.