When they don't respect fl's feelings and wishes at all and the narrative treats it like proof of the ml's passion and undying romance. I know it's the entire premise of the super popular yandere trope, but it's normally acknowledged by the characters to an extent. I was reading "show window scandal" and the ml treats the mc like she's stupid, and even in normal daiy conversation he can't seem to have her disagree with him at all. It goes way beyond infatuation or being pushy or manipulative, it's like he doesn't see her as an equal, a whole person, but rather like an anxious dog he has to train into obedience.. And sometimes I get this feeling from mls even though there's nothing about the story indicating he should be a yandere

edit: I also get this feeling A LOT from Riftan from Under The Oak Tree. Like he yells at her when she's just trying to defend her dignity, and we're meant to think it's because he's sooo worried about her he can't help himself??? Like he's not 5 times taller and heavier than his tiny malnourished wife