Komaki noticing Wakaba's warning up to doing physical things with her and still doubling down on being a shit to her. Is it any wonder Wakaba's stance is that Komaki is pretty but too fucked up right now to want to be with?
I don't think Wakaba's issue is primarily with the treatment--she seems to enjoy the treatment, though is a bit ashamed/in denial. The core issue seems to be her believing Komaki doesn't like her. If she knew Komaki likes her, I assume things would be different. Komaki's behavior makes it hard for Wakaba to understand things but that's intentional on her part and part of the "fun," for us.
Also, Komaki didn't really cross the line Wakaba made, which is why Wakaba asks again for Komaki to actually be rough with her if she indeed hates her so much. She seems to feel Komaki is treating her too nicely for someone who is supposed to be doing despicable things. This "gentle" treatment is also further intensifying Wakaba's feelings for Komaki which continues to make her uncomfortable ("chest aching" and all that). She'd rather be treated in a way that actually is terrible, so she'd not have these growing feelings.
Wakaba physically enjoys the treatment, while at the same time considering that treatment as proof that Komaki doesn't actually love her. That's why she keeps talking about what Komaki really loves. Right now they've got a somewhat functional sexual relationship but not a romantic one, in Wakaba's eyes entirely due to Komaki's feelings. She seems to harbor a hope that if she can beat Komaki at something she'll chill and stop being so weird and then maybe romance can happen.
