Me too. Even ones where like, all the other characters, male bystanders included, tell the MC that they're weird or dumb - made it through fine. I'm having a much stronger annoyance/disgust response to this guy than is warranted by just his density, and I'm having a little trouble putting my finger on exactly why. So I'm hoping somebody in a similar boat can explain it and have it click for me.
Maybe because without any kind of explanation of what he thinks is going on or why it's not okay, we're left to assume that the manga regards his behavior as either normal or obviously understandable. And I get what's happening, and it's obviously That Trope, but that's not good enough to be a character's motivation, here?
If he doesn't have an alternate theory of what's behind Mafuyu's actions, then I need an explanation for why he doesn't take a normal course of action like matching her pace and flirting back because he's into it, or rolling with it because it's just quirky behavior from a childhood friend, or telling her how uncomfortable it makes him, because reaching panic attack levels of distress over this and then just acting a moment later like it never happened hits weird. Or show us that he DOES have an alternate theory and that there's some misunderstanding and their motives are at cross purposes or something, like a good reason he wouldn't want to be seen with her, or him trying to set her up with someone else. Anything at all.
If you don't, it defaults to "he thinks intimacy is icky and it makes him feel all weird and he has like, a clinically significant reaction to it" and "his subsequent passivity and fear of conflict rises to the level of hurting the people who care about him," which is a real fucking bummer to read.
Edit: For clarity and to remind those who have forgotten, Mafuyu is reintroduced to him by sitting down in front of him in class and saying "I don't date anyone because that spot in my heart is reserved for Tendou Souma, and I want to cherish these feelings" and Tendou Souma, yes, that one, sitting behind her thinks to himself "lol, it reminds me of a manga." He knows what genre of manga that is, and what the girl saying it means. Her bestie then excitedly announces that he's her first love, to his face, and drags her next to him, after which he can't focus on the lecture because of how attracted he is to her.
She's kuudere-ing out and overwhelmed, but there is zero room for him not understanding that she's super hung up on him, and he's way into her. That's not "density" anymore and goes beyond the boundaries of that trope.