
Yes nothing really bad happens to diana, she sticks to her morals to the very end and got an ending according to that. *spoilers ahead*
Her crown princess status was taken away, she and helio divorced and she went back temple to serve the god. I said its not really a bad ending for yer because serving the god is what she will choose no matter what. She didn't change until the very end,for her she was always right.

Im pasting this from another comment: he didnt give up just randomly he was doing his duty as a duke for the kingdom to prevent as much of unnecessary tension that could come about from his actions. Like obv him not accusing diana helps the emperor and diana the most but he also was doing things that would result in the minimal amount of chaos from the public in addition to wanting to focus on his relationship with uh fuck i forgot the black haired ladys name

I got jumped on when I had the exact sentiment. Like its cruel to torture a that guy but he did not really face that depression yet from the first life because of Hestia, upto a large extent. But he goes on kinda (not totally) ignoring and even helping the reason of depression. Like, each and every character has a reason for acting why they do except Diana, but i was seriously dissapointed with Kael at that moment! Like the best revenge is moving forward and leaving your past, that guy wants to move forward, leave behind the past without leaving the place itself. ahhhhhhhhh...
I remember reading a scene where Kael did not proceed and decided not to destroy Diana anymore.
So it took a large blow on Hestia and lost her reason abt living inside the novel.
There was this day which she went on the balcony thinking about ‘going back’ to her normal life in Korea. (She always thought that she was just an extra in the story so her leaving will bot affect the ppl at all).
Kael saw it and rushed to her ‘cause he thought Hestia will do S-word. He was frantic and apologized to Hestia. They made up somehow. Hestia fully accepted it when crown prince admitted that he made Kael do it.