basically what kurogane just told fai:
“you used magic in order to escape from lecourt, which contradicts your character goal stated in koryo to not use magic so your past wouldn’t catch up with you. even though you will not defend yourself if someone kills you, you used magic for the sake of our group, because your love for the kids outweighs your hatred of yourself and your fear of your past. even though you’ve tried to be distant, you still grew close. you love them.”
(unsaid: “that’s a good thing. you’ve changed for the better, and i’m sure you’ll continue developing into someone who can live for the future. i’m proud of you. i will do anything to keep you alive. i love you.”)
what fai tells him in response: “i don’t want anyone to get hurt because they were involved with me.”
what fai means: “it wasn’t me being kind. it was me doing my best to mitigate the effects of being a literal human curse. i am guilty enough, and i don’t want to taint those two children. it doesn’t matter whether i love them or not. i’m going to hurt them, and i’m going to have to kill you unless you kill me first, and i’ve fucked up by growing close to you. it doesn’t matter whether you think you love me, or whether they think they love me, or whether i love all of you: i have endangered you by my very presence. i am not worthy of any love. i am sorry to have tricked you, and even as i know this i keep coming back for more.”
and then the confrontation in the reservoir happens. and kurogane proves how far he’ll go. and fai realizes how close they’ve all become. and he withdraws.
kurogane: hey you’re a good person
fai: im a literal curse but nice try