Even though it's a small chapter

they are talking about it because Ren is suspicious Haru had sex with other women while they were in Canada (the second time) And for a child, that's very traumatic because he explained before that was a big blow on him :( of course they need to talk about it, in fact they don't mention it enough! Haru needs to apologize if he did it, Ren suffered a lot and that's why he doesn't completely trust him. I even bet he thinks Haru is still doing it. It's horrible and I find him very toxic for telling Ren not to do other things with other men and even going as far as to tell him to don't go back home if he had sex with Natsuo. He doesn't even see Ren as a lover, he often humiliates Ren when he asks for something else and the poor thing is caged inside a relationship he feels insecure about because he wants a family. Yes, he loves Haru but he doesn't think Haru sees him the same way Ren does

I get most of what you said. But, when there is an issue, you talk about it, settle things down and move on. When Haru came home smelling of soap and perfume they were NOT dating so Haru doesn't have to apologize for anything. The only thing he needs to apologize for is being ambivalent with Ren despite making a move in him. If you remember the novel, you will remember Ren thinking about this past incident and having an argument with Haru and even telli g Haru to his face that he doesn't like women hanging over him or smelling their perfume in him. He even came in terms with it, though he said he can never get over it completely. My question is, as we already know all of this, it doesn't serve anything in terms of plot development to bring it up again. So I felt the auther has repeatedly using the well explored feelings to bring in another dimension, namely Ren growing up. You think it's the only way to do it?

PS: pardon my lousy grammar, my phone is changing it on its own