Although at first glance this appears to be the trope of "boy is rude to girl because he doesn't realize he likes her," the story is slightly more nuanced than that. It's actually a double up: boy is rude to girl because he doesn't realize he likes her +
girl is rude to boy because she doesn't realize she likes him. This isn't a story of one-sided bullying - it's mutual antagonism.
Most people are aware of Rockmann's provocations, so I'll just list out Nanalie's, to show that it happens on both sides.
Some examples that made it into the manga.
(1) Ch 1. Upon their first meeting, Alois challenges Nanalie to a game of rock paper scissors, wins, and smirks. Nanalie... immediately decides that he's Public Enemy #1 and she never wants to lose to him ever again. Sure, he's a brat, but she knows him for two seconds and decides "okay he's my rival for all eternity."
(2) Ch 2. There's this really big panel of Alois smacking Nanalie right in the face; rude, right? Did you notice that a page earlier, she was actually the inciting antagonist of that situation, smacking the back of his head
for no reason other than because he was there? We get him throwing the first punch later in the same chapter so I'd call that tit for tat; the story can't show every instance of them fighting, but it does clarify that both of them instigate depending on the occasion.
Some examples specific to the LN.
(1) Remember how Alois challenged Nanalie to RPS once when they first meet? Yeah, she challenges him to 100+ games after that. I've heard how "ladies don't start fights but they can finish them," but she just... keeps going lol. It fuels her even further into Rival Mode, even though she's the one asking for all these RPS combats in the first place.
(2) When Alois switches from a smile to deadpan earlier in Ch 2 before the flashback to their meeting, Nanalie thinks it's disturbing how he looks so expressionless - and then chimes in that he'd look creepy if he smiled at her too. It's a bit of "damned if you do, damned if you don't," because she doesn't like him so she won't like
any way that he acts.
(3) It's not
completely cut out from Ch 8, but most of the nuance is lost, so I'll put it here. In the manga, after the masquerade ends, Alois pats Nanalie's head and says he had fun, and Nanalie brushes it away. In the LN, it's described as this:
He adjusts his glasses with his middle finger, taps me twice on the head with his hand, and rubs my hair a little, as if it is entirely natural for him to do so.
I smack that hand away without a moment's hesitation. To have my head rubbed by this bastard! It's completely humiliating! Worse, it's insulting!
Right after I smack his head, he comes back and lightly, or actually, firmly, whacks the side of my head. Ouch. That hurt, you know?
There's something funny to me about how she reacts rather violently to him, only to complain when he retaliates. It gives me the feeling that she's a bit of an unreliable narrator, as the story is so often viewed through her lens (the lens of still thinking "I feel funny; I must hate him!"), meaning the narration is bent through said lens. The reactions of those around them, to me, are the more accurate determiners of what their relationship is more properly like.
Alois has realized his feelings, but Nanalie's still in
Loathing Mode (thank you Wicked for the great song). They repeatedly bring out... not the worst in each other, per se, but the most childish in each other. All in all, one-sided cruelty resulting in romance isn't my thing, but I'm totally down for two stubborn idiots incessantly bickering for ages before they realize how they feel lol