Text book alpha fucks beta bucks, fellas.
Alpha "dbag" ex bf used to dick her down and make her feel like a woman for 3 hours on end.
Current betatard bf has tried negotiating (mistake), talking to her doctor (mistake), and communicating (mistake). yet he only gets 15 of bland sex.
OP then asks for advice on how to further negotiate and convince his gf.
Commenters tell him he should manage his resentment. He should get counseling. That "it doesn't matter who fucked first. Only who she fucked last!" (barf). We all do dumb things when young!
Totally shit responses. Telling a man to just ignore the fact his woman gave better sex and wanted to satisfy another man more...is not understanding men.
This guy needs to learn that sex/attraction is non-negotiable. You don't convince and logic your way to your gf riding your dick for 3 hours. Her ex insisted on that type of sex. It was his nature and identity. So she had no choice but to follow that because women are going to follow the frame of a powerful man who reassures her.
This beta bf lacks that.