No matter how human like he acts in her presence and in other peoples presence, it wouldn't stop the fact that he is a demon and he needs to feed in ways she wouldn't like.
Listening to Miss Marceys words had made her calm and immediately reduced the fear she had. Not to say she has also mentioned that if Ethan were to notice that the scene he had caused seem to have affected his growing friendship with her, he might manipulat her brain into forgetting. Now, it wasn't that she didn't want to forget tonight or wouldn't be willing to, but she didn't want to forget the forehead kisses and how physically close they had been. Even though a part of her felt very uncomfortable being like that.
