Nothing. I do too. But I think the author wants to show the disparity between the two, just like the MC imagines: she, an unreachable princess, he a lowly commoner. She, the princess, is lonely and unloved, even her servants don't eat with her but he, the lowly commoner, enjoys his meals with his kid sister. She is unhappy with her life but he is perfectly happy and content.
I like eating alone when I choose to eat alone, and I like eating with others when I choose to eat with others. it's all about having the choice and freedom to choose, which shindou didn't have until our mc offered her lunch/dinner.
I'm betting early on, she's a simp, I'll give you 20 bucks if she ain't
Anyway, I really like MC, he has, personality, I heard in a lot of mangas they don't have Personality . But, I guess it mostly just the shounen ones, I forgot if this is shoujo or shounen so maybe that's why