On why he sucks: in a relationship, if the person cheats, the one at fault is the cheater, not the side piece. The cheater has an obligation to be faithful as that person's the one who's in a relationship with you. The side piece has no obligation to be faithful to you. She's not in a relationship with you. He is. So he sucks. I don't care if he likes her later. It's hopeless, but I hope MC ends up with someone else.
But by that logic wouldn’t he be cheating on rose-bitch because he was dating her first and for one whole year. He is staying true to his pervious relationship it’s clear he only married our MC so he can promote his mistress. And that makes him an asshole cause he’s using other people for his own selfish reasons

MC's a bad-ass. I don't want her to end up with the Emperor. He sucks just as much as that Rose lady.