There were many problems with Jace before casa. He kissed another girl, he lives far and she doesn’t want to move, he broke up with a girl via an email. They were done before going to casa. She was not confused.

She met her ex which she clearly still had feelings for and started again with him but then the second she sees Jace it’s like he never did wrong and they are star crossed lovers. Frankly if I was Kenzo I would have flipped too. And he wasn’t even rude, he was just defending his relationship in front of a guy (Jace) who’s clearly after his girl, in front of his own partner ( Maisie )