the Duke actually doesn't seem as unreasonable. I think most people try to make their exes or crushes jealous, regardless of whether that's right or wrong. in the original, since violet acted so shitty to shannon, that was probably a huge turnoff and only got worse from there. now that it's dahye, she's less villainous, and the Duke is still in love. it's true that he's too late tho.
tldr: F.