it's not him being dumb imo, its him overthinking as an overthinker myself i tend to also get caught up with my own thoughts if im left alone with them and its hard to stop that. I do agree that if hes thinking so much why didnt he just think to talk to kitaoji but thats the thing you dont want to burden the people around you. You dont want to make them worry about you but he didnt know that by doing this it creates tons of misunderstandings and makes people worry more, im glad they eventually talk it out and you can actually see the raw pacing of problems like these like they're not quick to solve because when you want to talk about it you get scared of the other persons response
This is just me, but after reading this again…Arima has these dumbass moments. Kitaoji shouldn’t have to deal with his partner lying all the time about small things, like I understand his insecurities bc kitaoji was originally straight, but to keep pushing this narrative on him that he would leave quickly for a women is so shitty. Kitaoji literally dealt with his shit twice already and probably is gonna have to deal with it more. It’s like Kitaoji said, he starts things and then ends it on his time and doesn’t think about how Kitaoji would feel. If my partner did that I think I would leave because I wouldn’t deal with someone looking at me in a distrustful way just because of their insecurities. It was like the author had to write a “dumb bitch moment” in order to carry on the story.