say nothing, unless she asks your opinion, and then be very careful!.......maybe say that it looks fine, although you really liked the way it looked before!...........but hey it's still her, so it's fine!................
glad you're not that brave barron, you shouldn't tell her, just let her decide herself!.........it is her hair after all, and if she likes it, then you need to get used to it!....
Ok barron, so she wants the back shorter, let her have what she wants!.....as I said, it's her hair, and if she feels good then that's what it's all about!.................
Oh barron, you'll be ok, it's only a haircut after all, the person is still the same!..........Don't stress about it!...............in a few months, there'll be a new haircut!..............