However affronted people might feel at the moment, bear in mind that Jem is more likely to be acting out of genuine concern for her sister than the obsessional Anton will ever be.
What Jem said wasn't all that bad if you sit and think about it, she didn't say that he was pretending to like Faye, and went to great pains to reiterate that she believes he
does like her, when it was Faye who immediately worried about that.
I don't think that poor little Anton's bombshell is going to have the seismic impact he thinks it will -
Faye has already heard it from her sister and seems at the moment to have largely dismissed any concerns. She's already cautious so absent some other 'evidence' I can't see her suddenly having a change of (importantly!)
heart over Aaron.
Louise might give the idea some weight, since, lets be honest, she's not a great thinker, I doubt she's going to analyse it much.
Tom will probably want to believe it because he still feels a bit betrayed and hurt from earlier when he was 'crushing' on Aaron.
I suspect Alex and Harry will both probably regard it as faintly nonsensical since it won't chime with their experience, and will ascribe Jem's doubts to the short time she's been in the house with Aaron personally and sisterly concern for Faye.
And Aaron knows that Jem isn't his most enthusiastic supporter and knows well enough why that would be, so he isn't likely to really care.
Don't 'punish' Jem for having what are no more than doubts, and thus allow Anton to slip through the net. Without the egregious buggering about, he would be gone this weekend anyway - let's ensure that normality is restored!