Anyone who says she's just lustful towards MC hasn't really paid attention, in EP6 she asks herself why her feelings can't just be carnal, which was basically already confirming by then that she already felt something more for MC even before she accepted those feelings, but her confessing to MC that she has feelings for him happened earlier than I was expecting tbh. I always thought Jill would be the first one, but considering how fast she's opening up since EP7, DPC might actually pull a fast one on us, make her say the "L" word first and curb some expectations along the way.
And regarding the top 3 student discussion, I'm still not conviced Bella was 100% honest, at the end of the day she's his teacher, whether you end up friends or lovers, the conflict of interest is there, so perhaps she's trying to distance herself from him in terms of class related stuff to try and avoid any kind of favouritism towards him. I mean, MC can literally ace every single evaluation and still she doesn't acknowledge him as one of the best? C'mon