@Arkal97 hmm well I'm still trying to figure out exactly how I feel about the characters and why, so sorry if my explanations don't make sense or are a little contradictory haha
i do agree that You doesn't really deserve this much more hate than the other characters. all of them are p gray (which to me is good bc that means that they're being developed), which is mostly why i like reading this series (although saying i enjoy it is kinda weird when i spend every chapter yelling at the characters to stop their pain and get divorced hahaha)
personally, i feel like cheating is cheating so the fact that You only cheated once while Michi had an ongoing affair doesn't really make him seem better in my eyes. they're just both in the wrong lol, and him trying to work on the marriage now without even coming clean to Michi doesn't seem enough. (this of course doesn't put Michi in the clear about hiding her own affair, so tbh i see them both in the same bad boat)
i don't really want to say that much about how he's trying to change now bc he's only just started, so i wanna give him some time before I judge his efforts too harshly, but i do feel like his reasons for starting to communicate and make an effort to treat Michi right are more self-serving than anything else. so right now I'm not really too excited about him changing bc it seems like if it doesn't get him the results he wants, he might revert back to how he was before. but we all have to start somewhere, i guess
but tbh i see what you mean about Niina just getting worse bc he wants to keep going with Michi and divorce hasn't even crossed his mind like he could at least separate from Kaede (i think that's his wife's name haha) before trying to pursue anything. (can you tell i just want them to all separate and stop needlessly hurting each other lol)