Yesssss what an interesting twist! Normally I hate the whole 'actually the FL/ML/characters of the novel were really evil all along!' kind of thing, but since we're in the pre-story timeline and not in the actual novel it's a lot more interesting to me. Plus the unreliable narrator really opens up a lot of stuff to be questioned, and raises the stakes a lot more!! Exciting!!!
I hope that Deborah and the temple aren't in league with each other like a conspiracy against Abel or something - I'd have to go back and reread the parts that involve the 'actual story' details, but with the borderline eugenics-y way that Aisha's family only marries other light users, the temple's hoarding of light users, and the description of Deborah that says she's the only one who can use light magic as she pleases, it makes me wonder if Deborah's actually a child whose existence slipped the temple's leash, so to speak. Ahhh I wanna know!
I bet the temple's behind Aisha's father opposing the marriage as well, it's suspicious.