Inspired from rant in the credits: I'd argue that this story is, in fact, quite cliche, despite not being isekai, it's a "fake marriage on mutual benefit after breakup, with drama about wealthy families in medieval fantasy (?) world" kind of deal that was done to death, but for me what draws me to this manhwa is it's artstyle and characters, and most of cliches used are beneficial for that character-focused narrative with more drama and more fluff available because of setting and overarching plot.
EDIT: Removed spoiler because most of what I say is unrelated to the point of that rant.