
I didn’t really understand what she was jealous of. Can someone explain it?

Actually, if you can remember, Bachiko tried to give her own handkerchief to Iruma so that he would escort her as her student but Iruma had to politely decline because he had already promised Ameri to accompany her to the Deviculum since he received her handkerchief first. So in short she was acting jealous towards Ameri because she felt Ameri robbed her of the opportunity and was envious of her. :)
Dropping. Sorry it feels like we’re back at square 1, and square 1 was a horrible place to be.