Why does EVERY guy I date do this?

So every guy I have ever been in a relationship with has always taken me for granted.. I chased them until I finally gave up and I always gave my all into relationships. EVERY single one of them has contacted me after some time, apologizing for not treating me right, and some even asking for second chances.

I don’t understand why this happens. Why I have to go through hurt for people to realize they’re treating their partner unfair? I am always the one trying the hardest in every relationship.