Have you considered Rosaline? It's not so different from Rosalie, but it changes the ending you don't like. It's also not such a big deal to change her name then, because the difference is only the matter of one extra letter. :) You can also choose to pronounce it Rose-ah-leen or Rose-ah-line.
Hi- I did consider Rosaline w/ a long I but b/c my name ens in -ine it seemed too matchy-I do find it intriguing though. Pronounced as Rosaleen is interesting, per the "Dark Rosaleen" reference and as someone mentioned, but not sure how I feel about the -een either, thank you for the ideas though!