Responses
I 110% agree with everything you just said.
Me, three. I mean if Harada would give us a sinister ending with bad omen written all over it, I would have sensed it. Sensei never hides her intention. If the story's future is dark, we would've known it for sure and Sensei would give hints, even if the ending is seemingly happy. Reading all of her works, I can already tell if a page or panel has some underlying dark stuff going on but I swear I felt nothing. Just a twisted yet liberating kind of ending.
Considering the mental and physical torture he just went through, it comes at no surprise that Nii-chan looks so dead inside by the end. I don't think it has anything to do with Yui really.
I too would look like a disaster if I went through what he went through. When you're that emotionally drained, you don't express emotions. It's extremely difficult.
So I would be more surprised if he looked well at this point.
Take it how you will, but I personally don't necessarily see it as a bad omen for their relationship.