I remember there were a couple chapters where the protagonist was kidnapped by the husband‘s lovers little brother who wanted to marry the protagonist so his sister could marry the husband.
The protagonist wants to marry an old rich guy instead because he’s a more stable option then her husband because he’s handsome but useless.
The father of the protagonist also seems like a bad guy, but does some good things, like saving children and refusing to hurt them. He definitely has an ulterior motive for marrying off his daughter to the husband though.
OH i think i know the one?
https://www.mangago.me/read-manga/i_ll_divorce_you_gracefully/
is it this one?

I read this manga a while back and want to reread it. The plot was a the protagonist gets engaged to a guy who already has a lover, so he hates her and thinks she’s evil like her dad. As time goes on, the guy realizes that she’s not evil and doesn’t take after her dad who seems evil. His former lover gets jealous and tries to fight her, but she soon discovers that the protagonist is also secretly a really strong knight that she admires. The husband eventually falls for the protagonist but she wants to divorce so she can be free.