The Emperor of Croisen hated Empress Yvonne. Enough that he’d wish for her to disappear three time...
FL is an empress forced onto ML by her father. Typical abusive father + hateful husband who brought in another woman. Her mom was the only one who cared for her. ML & FL has some past, but she's cursed so she can't speak about it. ML tries to kill her repeatedly but when he realises it's all a big misunderstanding he regrets.
regret part is apparently good enough to suffer through the heartburn.