I may be saying an unpopular opinion here, but if all your relationships end up like that... you're the common denominator in these failed relationships. I find that a lot of guys that are self-proclaimed "nice guys" that "do everything" for their girlfriend are amazingly pushy in a relationship: coming on way too strong, way too fast, and being far too clingy. I've never cheated in a relationship, but something like that has pushed me away from a guy before.
I obviously don't know you, and what I'm saying may not be right in your situation... but I'm just pointing out some observations from personal experience.