I haven't read any of the updates for the novel, but your rant honestly makes me relieved that the manhwa is making a lot smart and creative changes to the story. While I understand why the twins stopped Donau from confessing to Paul because it would make things worst for Paul once he becomes officially engaged and create a bigger scandal in the eyes of nobility. Earlier I said I didn't like that Donau didn't confess his feelings in the manwha, but now I change my mind. I like that he came to the conclusion that his feelings would be a burden to Paul on his own without having anyone hold him back. He alone realized the kind of problems he would impose on Paul and his family (since they don't have a high status) and he doesn't want anyone to suffer. But at least in the manwha he was given the chance to sincerely wish from the bottom of his heart that Paul find the happiness she deserves and I honestly find that to be really sweet of him. So now, I do believe he got proper closure for his feelings. I also want to point out that his narrative is one of the few that doesn't bring up all the shitty opinions that Paul is "ugly" or whatever. He genuinely sees her for the amazing person she is and loves her for it. He is honestly a great dude.