Literally
Sir Erichter was just obviously in love eith her, but childish af because he didn't know how to compliment her. He heard the phrase "boys are mean to the girls they like" and took it as a life lesson. Pisses me off.
I assume he resents her because he probably hears a lot of shit because she works hard too hard (especially being one person FOR one person), making everyone else look like they're being lazy and not loyal enough. He probably gets criticized by the imperial family for his low loyalty, but really, MC had a stupid amount of loyalty.
Overall, he's the kind of person I hate the most. Just takes out all his frustrations out on her and doesn't communicate properly like an adult. "Thanks for worrying about me" my ass.
He took the tsundere archetype to the maxxxxxx seriously he’s just mean
The couple is great but my blood boils cuz of that one annoying character, he's not even anything to her but criticizes her every move, dictating her and shit like he's not her family, superior not even a fuckin friend, he's just a junior collegue but he gets to just treat her like that? Both past and present he's a piece of shit even if he gets a redemption arc or whatever and falls for mc. I can't believe she's just brushing his rude actions as "concern" when he's nothing to ber. She doesn't need his pathetic "concern".