I think we are meant to thematically understand Anne-Marie as a reflection upon/judgment of the hypocrisy of society -- she gets blamed for telling exactly the same kind of lies that all the adults around her also tell, she just doesn't understand the rules for how/when to tell them so she becomes scapegoated for it (and indeed Awful Jock's downfall is through a classic Anne-Marie Helpful Hypocrisy in lying to Sylvia about how much he likes Anne-Marie!) -- but then whence all the deaths! Is she also just unrelatedly cursed??

Perhaps Sylvia was the true self-appointed saint all along .... she really does seem desperate to throw herself virtuously on the Pyre of Anne-Marie, presumably as expiation for the death of the priest.

I have to admit that I am somewhat glad that Lindop has finally followed "teen girl with a crush on inaccessible older man" to its logical conclusion, "and then I finally got him and it was simply the worst, and he was an enormous asshole, and I also had to worry all the time about accidentally giving him a heart attack." I thought she probably did not at all want all those teen girls to get their unattainable men but it's nice to have it confirmed!