It wasn't that he didn't actually feel sad. At the beginning of ch4, it started with Honma's (seme) thoughts: "The trick to not feel lonely or sad is to life to yourself." and it showed him and his brother at their parents' funeral. So in reality he *was* sad when they died but he's been lying to himself all this time and only stopped after dating Ikai (uke). So i guess the sad feeling we felt for Honma was bc previously, his life had been empty (for lack of a better word)? And i guess we were subconsciously wanting to see him continue growing? Idk where i was going with this lol
**lie not life oops lol
the seme said " to survive, you need to lie" I guess he is actually lying to himself a lot that lying to others seems like a normal survival tip. I think it can be interpreted on each people views but for me, I think he meant in order to continue the life normally, he has to lie to himself that he did not feel sad of his parents passing away. If he keep being sad, then he can't fully finction in his daily life. Thus, lying is an option.
Ok to be completely honest, this was cute. But, I don't know? Something felt wrong? I feel sorry for the seme for some reason. Also, I wish they revealed why he wasn't that sad when his parents died.