Now u just reminded me of that and I think your opinion it's pretty valid, I just want to say that it's still too soon to judge him as a hopeless character (IMO). And no, I don't even like him and for me, he could just get lost and I wouldn't feel anything, but I'm talking about this because of the overall value of the webtoon. I truly believe he has a purpose and all the characters in this story, so I think he can redeem himself somehow in the future.
The situation you're talking about could have lead to what u said "r*ping someone" indeed, but there are other details that make me doubt that he'd reach till that point, which I think it's something you're forgetting in your equation and are valid as well. In Robian x Princess' relationship, his character has never had power, I'm not saying this to excuse his actions or some sh*t like that, I'm saying it because he has never thought or felt that he could ever do something without the Princess' consent, that's why he begged and asked for her to USE HIM because he wouldn't ever be able to truly push her. His attempt wasn't of raping her, was of begging for her attention and that's different.
He began forcing her and yeah, that's disgusting and crazy and he has to pay for that (he's paying for that), but in the end, he always puts himself below of the Princess. All the male characters in this story (except for the Emperor) tend to put themselves in that hierarchy or relates to her under that structure of power (the reason why I think Yuriel, as the only other female character, is the only allowed to try to kill the Princess in the story), so I think that's the base that will open the doors for other characters who're not in the MC's side to become better and finally be accepted to be by her side.
Everything you've said it's pretty fair, that's enough to dislike him and I do agree to it now that I've remembered more of his previous actions, but I personally think that none of those things makes him the worst character ever without hope of a 2nd chance. For example, talking about him verbally abusing Nadricka (which is my favorite character as well), he's doing so because he's jealous and because that's the only way he knows (for now) of how to convey his message of 'protect the princess' towards him. Does that excuse his words or we have to forgive him? Nah. Does that transform him onto the most horrible monster without help and hope? No. And that's my point, he has to pay for what he has done but he's not an entirely horribly character, he's manipulative but he's showing that also can be a characteristic of him that can help and save the princess. He's not black or white and probably none of the characters are like that so I (this is my opinion, for now, it can change in any moment and u can agree or disagree without problem) am not that rushed to treat him as the worst character (yet) and not giving him the chance to become better.
And listen, I truly don't care about defending a character, so u can hate him all u want, lol, I'm just writing all this because I want to be open to all the characters' development. Maybe what I wrote makes u think that I think what he's doing is acceptable, but instead of that, I'm just saying: it's possible. It's possible for him to act like that, and be a character like that for now, and it's also possible for him to change and be a better character in the future. Thanks for reminding me of what he did (seriously). xd
Edit: You truly made me think of editting my other comment because I forgot about what u said, but I still stand by the idea that he can change and redeem himself, ofc you're free to feel however u want. c: