Honestly, how bad is the allergy? Like, is it a full blown anaphylactic thing, or does she just get a bit sniffly? Seems like a weird name choice if it was truly life threatening. Maybe she just doesn't like them and calls it an allergy to avoid explaining.
yeah I actually read somewhere that there's this whole thing called "emotional allergy" where some people are so traumatized by a specific scent or thing that their body reacts like it's an actual allergy. could be she had a bad experience with roses as a kid or something. or maybe it's one of those weird real allergies that developed later in life. i knew a girl named Daisy who was allergic to daisies, it's actually pretty common for people to be named after things they can't be around. still feels like the universe has a weird sense of humor about it though.