As someone on the spectrum I had the exact same thought from the get go. I'm also very stoic and careful with showing my emotions to people I'm not sure I can trust yet, it's me being wary and unsure of how the other person will react, and early on in my relationship I struggled with communicating my feelings thinking if the other person cared enough they would just know what I was upset about based on the situation and their not knowing just meant that they didn't care and didn't love me enough to pay close enough attention to what upsetted me, which was silly ofc. So I've had to get used to plainly stating what I'm upset about when I'm upset about it and naturally things have gotten a lot better in my relationship as a result.
I've found a lot of women especially young women struggle with this also though, because of the fictional men in media who just know whenever something is wrong without the woman ever telling him, and we all have to realize that's fiction and not what a real relationship is like.
Omg I can't like your comment but I just wanna say I agree with you!
I think mamiya is v cute like a black cat even but hayato, is LITERALLY A MOUNTAIN full of a GREEN forest. I understand Mamiya is pretty unsure in his relationship but I feel like he doesn't understand that his partners can't read his mind nor does he tell/clarify to them that he DOES like them but that he doesn't know how to verbally express it(?).
For me, it feels like he doesn't think he actually needs to verbalize that his feelings for them are mutual: that he also likes them back. I also feel like he might be on the autism spectrum tbh but idk I don't want to assume lol. Anyways, ig his partners might feel like , even hayato, that mamiya doesn't like them bc it may feel like they're putting in all the effort into the relationship