Is it normal i regret getting into relationships with girls?

Everytime i get into a relationship with a girl, about one or two weeks into the relationship i start to get this regret feeling and it hinders the relationship.
I don't know what to do to surpress this feeling. I do have anxiety so i think that might have something to do with it.

P.S. I'm 19 years of age and has bothered me for my whole life.