There's a fine line between bdsm and rape. They are not the same things, I can see that the author might want to add it but where's the trigger warning? Are we to assume that abuse is a normal part of bdsm? Even the Wookyung rape scenes are just called "graphic bdsm" while Duna's rapes have 0 warning. Let's not cut the author slack for clearly misrepresenting the bdsm community. Giving warnings is very simple, just a small note but it means that the author understands the seriousness of showing assault in a romance/bdsm manhua. Some may be immune to it but it shouldn't be assumed that people are going to be on board with a sudden rape scene.
People in the comments complaining about the sadism in a book literally called Sadistic beauty