I mean the orignal Duchess literally dies so like it's not just about simple ignorance
She already pitied the orignal Duchess while she was reading the novel so I honestly don't blame her that she doesn't care even a little bit about him
Maybe because of the translations here that's why you didn't understand the FL, but she did say that if she's just a reader or a 3rd party, she might be able to understand the ex-husband situation. But because it's about HER now (someone who'll suffer and die if she stays as a Duchess) she decided to divorce him and let the ex husband and pink hair be together.
I mean yeah all for the divorce but it's the same sht of ml isn't abusive just ignorant of his own actions but in other stories, people still root for him. It's obvious there was something about the past that the author is purposefully hiding cuz it's important to their story and connection and it's obvious too that Dilov needs Seira cuz of pian (like Espers and Guides situation) which means it could end in him losing himself to the power but she's like "money money money so what about your situation that could lead to death" Annoying af