
I think yuuma has a good reason though. someone with split personality you have to be careful and I think as he likes Rei he likes them all as they are all rei but each are technically their own and he feels conflicting saying no or not liking one because he would be pushing away a part of rei in his mind and doesn’t want to hurt rei or Kazuhiro. He does know he doesn’t want him to touch him like rei and doesn’t really know how to express it to them both clearly. I think he’ll get there though hopefully

Seriously, I agree with you and the translator. The sex scene or rather part-sex/part-rape scene, while really hot, was uncomfortable to read.
Though, I'm glad that for Rei isn't blaming Yuuma for Kazuha's actions, it can lead to bigger problems like trust issues and uncooperative behaviour between Kazuha and Rei (which was essentially my problem with Kill Me Heal Me).

Rei said something like “see so you were kissing him” to Yuuma, even tho that’s more linked to his personality than actual blaming, I feel like Yuuma is walking on very thin ice and it’s putting itself aside in order to handle this.
We are maybe reading too much into the manga and the author is definitely not exploring the yumma side of this stories but every time I read this I just think about something I saw in the past that went along with “ no matter how kind you are, if you are dealing with a mentally unstable person learn to step back and cut yourself off from them, because there’s no way For you to “fix them” without damaging yourself, it’s like fire, you WILL get hurt either from the flames or from the smoke”.
Yumma is getting burned despite it not being explored on the manga.

This definitely isn’t a normal situation for anyone so it’s hard to say how to handle it in any one’s situation but as rei is already self conscious of his disorder I think that’s why he keeps blaming him or feeling insecure. I think your right about playing with fire will only get you burned but it’s kinda like do the consequences out way the good and for yuuma the good out ways the bad so he’s willing. If rei and is other alters can work with him and I think they will through some tough effort
This sex scene was a bit uncomfortable to me, I felt like it was the most exhausting scene of the whole manga, the situation both Rei (for not being more understanding and stopping the whole interaction), Kazuhiro ( for basically violating Yuuma’s body, boundaries and feelings), and Yuuma (for not drawing a clear line to Kazuhiro about his true feelings, he likes Rei, and by doing that he is essentially cheating on Rei).
this was so confusing, I fell bad for the Seme’s but I feel like at this point, Yuuma mental heath would start deteriorating, because that’s a very tough and emotionally painful place to be.
, he deserves a break.