<human>: My girlfriend and I have been dating for 7+ months and things are going downhill and they need to be fixed. I have identified the problem as me being too much of a "nice guy". She even told me one night when we were both drunk that "I'm too nice and it gets boring". And she's right, at the end of the day I'm a doormat. I'm a pushover, I hardly ever get mad, I can't say no, and have trouble standing up for my self. I rely on her and put literally all of my effort into this relationship. Buying her food, clothes, gifts, etc and giving her everything she wants/needs while I get almost nothing in return.

Now my girlfriend has taken advantage of this and manipulates me. She's generally mean to me and never used to be like this because she knows she can without suffering any consequences.

How do I become that dominant, mysterious, commanding man that controls the relationship without being a douchebag?

Can you summarize the given text in a few sentences?
<bot>: Need to fix my relationship by stop being a "nice guy" and getting walked over without becoming a douchebag. Do not give me the "break up", "there are plenty of fish in the sea" answer please...