She blackmailed him with social ruination into their current relationship, which she casts as "fake" and "in order to chase away other boys". She keeps calling him "Loser" because she misunderstood his name, and never bothered to question why someone would actually be named "Loser". These aren't things filtered through the protagonist's perspective.
Clearly, neither of them have any respect for each other.
...he did the blackmail to himself?
Does anybody even remember how he was agonizing over how he didn't like getting strongarmed into this "fake" relationship? He hardly likes her, if only at this point-- and that affection is probably just sexual infatuation. He's gotten harassed and given dirty looks on multiple occasions over a circumstance he doesn't even want to be in (which is part of the reason he doesn't want to be in it).
"I don't blame her for how she talks to him" She is the only one who wants this farcical relationship (until the point the protagonist saw he could exploit an ostensibly superior position) and the only person who doesn't suffer from it. She is choosing to talk to him like this in a circumstance she chose to engineer and maintain, when she could have just ruined the guy's social life or told him off from the start.
He'd probably appreciate that, considering that this fake relationship wasn't his idea and he was blackmailed into it by her.
It's sensible to be fed up with the protagonist, but some of the overall reactions have been nothing but "halo effect" combined with forgetting most of the narrative up to this point.
I mean, you're right. I had completely forgotten about that. I guess I wrote it off as standard romcom tsundere-ism? I swear there have been similar starts to relationships in better stories.
My problem with his behavior is that we're 13 chapters in and have yet to see anything resembling a redeeming quality. Someone else mentioned dangers of my heart, which I haven't read, but from what I know the protag boy is something like "oh, you shouldn't get close to me, it's dangerous, I might hurt you", correct? Which, edgy delusions aside, indicates a kindness and care for others. This boy has just been... mean? Like earlier with the drawings, the mindset was explicitly "i'm too weak to do anything to you in reality, so i'll objectify you as a drawing I can do with as I please", which, once he thought he had even a modicum of authority, he attempted to do in reality. It's less that the comic is portraying his behavior as reasonable, and more that the reason I read romance stories is I want to see people i've been given a reason to care about form relationships with each other. I have been given no reason to care about this boy, unless I were to identify with him personally, as a self insert. I
emphatically do not. I can't see this changing any time soon, so unless it takes one hell of a turn, there's really nothing for me here.