You are in Hogwarts with Luna and everyone else, and you have Defense Against The Dark Arts as your next class, which is Boggarts with Remus J Lupin. Luna is Emetophobic. You can be whoever you want! (Sorry she sounds kinda like Marinette don't mind the voice)

Your boyfriend is cheating on you with Paisley, and tells u that she is your cousin. Paisley also thinks you are his cousin. Take it from here!