Sure, it might be true that he's an idiot, talentless and naive, but you can't repeat that to him every single day and every time you have sex! You gotta make it up to him dammit!
And although what Michiya did isn't any better than what Yuki did (at all), Kouta's not as naive or wholly forgiving like Chihiro. I feel like Kouta can think for himself and protect himself in contrast to Chihiro (who's naive and gullible), which is why I think most of the readers didn't bother commenting about the non-con element in the story. Michiya knows he's done wrong and is making it up to Kouta, unlike Yuki whom I don't think learned anything. Plus Kouta does demand compensation from Michiya in the form of... Good boyfriend acts?? Idk. He just demands what makes him happy, so... Oh well ╮(￣▽￣)╭
Not to mention this is yaoi following a very typical and traditional plot/route, so. Don't expect substantial justice (sorry. But I swear the genre has evolved and sophisticated over the years tho, and there are a lot more reasonable, and consensual, materials now)
Idk. I just find Chihiro more vulnerable than Kouta and deserves more attention and appreciation from Yuki.
Awww second couple needs more attention. Also, I was actually hoping that Yuki would suffer a little for making poor Chihiro so insecure and unsure of their relationship. Like, have him chase Chihiro a little, work hard a little bit, when Chihiro somehow managed to put a bit of distance between them.