@cor3zone I don't want to be rude and try to push my interpretation onto you, (I know nobody ever really likes that so I'm sorry) but I don't think the physical contact that resembles abuse necessarily needs to be abuse. The silly kana sound effect, the noodle arms, and blushing in response(embarrassed reaction instead of fearful), make it look to me like it's implying she's tapping him pretty lightly and it's overall very playful. This manga does after all make an attempt to show that Nagatoro and Senpai have begun to understand the other, and that Nagatoro has come to understand what's acceptable and what isn't. "I know how to hold back," for example, as well as when she tried to deal with how uncomfortable she had been making him by having him redirect his hurt feelings by fighting back.
Making lots of physical contact is a sign of romantic interest towards a person and I believe that it's just another way of showing her character's feelings, because she is all about being a sado/tsun-dere hiding her affection and being close to her crush by teasing them as a coping mechanism for her embarrassment and shyness. Literally like they say, "kids bully their crush," I guess. The fake physical abuse is an excuse for her to touch him and Nagatoro is an immature girl rather than a malicious one.
So I really don't know for sure if my comment will change how you see it at all, but at the very least I want to try to acknowledge, for the sake of readers that are uncomfortable with it, the fact that it's NOT a typical malicious display of physical abuse. And also, like I said, their relationship has evolved just a bit like coming to a mutual understanding of what's okay and what isn't like in a couple's S&M activities. (Incredibly relevant considering the author and the original doujin. A big point of the manga IMO is that wholesome love exists in S&M)
I know that in real life we can't put our full trust in relationships that look like this being healthy, because we can't know all that much at a glance from the outside. But in a manga it means quite a lot when we're given lots of signs that distance her from being genuinely toxic or abusive. IMO I think you have to look at what the little things are supposed to mean. She has stolen his food, similarly to the original doujins. But unlike the doujins, she gives food back or even tries to feed him. And unlike when she gifted him a literal dog collar(doujin), an earlier chapter depicted her giving chocolate. Again, I'm sorry if I'm awkwardly forcing my opinions! I won't try to say that you shouldn't believe that she should apologize and change. The most I think I can try to ask for is that we see Nagatoro as a girl that's very caring and affectionate but so immature and ignorant at times that she expresses herself in a detrimental way. So a conclusion here is also that the manga is actually just as much about Nagatoro's character development as it is about Senpai's.