Thank you so much for that advice, I'll make sure to update the tags later on. This fic in particular is a slow burn that starts with the characters as kids, so the scene where I actually break up the canon pairing will still be a bit farther in the story (and not really a large issue as of now), though I'm already conceptualizing a proper break-up between A and C, making sure to create a realistic and thoughtful way of doing so, because even if I prefer character A and B together, I like character C and want to give justice to my portrayal of them, and I really understand how unsatisfying it would be to make them have an unreasonable breakup (or extremely toxic breakup over cheating, for instance) just for the sake of my ship.