The reactions here are vile and unfair for a character that has grown so much. It pained me, to be honest. I just took it for what it was: he is experiencing immense stress right now, he's dealing with a the fact he has to be in charge of a mother who abandoned him and he loved, and now is in her deathbed waiting for the inevitable, and a father that never paid him a second of attention but somehow forced him into doing this. Of course his mind is in an incorrect place. Some people here believe they are the beacon of morality because they bash a fictional character for THINKING something that is wrong but don't even consider the possibility he did that because of something, and that is something that HAPPENS a lot to traumatized people.
Which bothers me is, the same as yesterday, somehow the rest of the chapter is not approved to be published. They bashed Kaji for not calling Fukami, and if they WAITED to read chapter 81 they would know he does exactly that. And develops a lot as a character in the conversations he has with Fukami in those episodes.
But well, it's always easier and gives you more engagement when you complain. First and most important Internet rule.

I dont know what the authors intention was when writing this scene, but it felt so ridiculous and completely nonsensical. Throughout the entire process of building a relationship/being in a relationship with Fukami, I dont remember Kaji ever thinking about cheating or having a casual affair. He constantly made it clear that he loved Fukami, and it took him a long time to convince Fukami himself that they should be together. I also dont remember him cheating on any of his previous partners, apart from being a playboy before getting together with Fukami. The fact that someone dated people purely for sex doesnt mean they were doing something wrong (judging someone based on their appearance is a different matter, although when it comes to one-time encounters, how else are you supposed to choose a partner?).
I dont want to idealize Kaji, but its obvious that he has changed a lot from the very first chapter up until now. Whenever he was going through a difficult time, he always thought about Fukami, so this sudden thought about cheating felt completely forced to me. It was almost as if he briefly forgot that he was in a relationship. Im glad it ended with just that one stupid thought and that the author didnt unnecessarily ruin the entire story.
Neither Kaji nor Fukami are perfect, and they both still have a lot to work through.
Ive never seen such strong and negative reactions before. Quite the opposite, actually, people have always defended and romanticized toxic, abusive characters, saying that “its just fiction,” so I was really surprised that in this case, people reacted so strongly to nothing more than the thought of having an affair. I dont want to sound like I’m trivializing cheating, because I think its absolutely vile.