Dude, do not be concerned. Unless she's agoraphobic (and I assume that since you married her she's probably somewhat outgoing) or a prude or a New Jersey Housewife, she will end up having a ton of fun. My wife is also not so much into the music (and we're in our 50's), but the cruise is so much more than just the music that she always has an incredible experience. My wife is artistic and creative, so she has a ball decorating the door and getting us into costumes. And especially because she is not so much into the music or the scene, I love to hear her talk about the amazing time she has on Jam Cruise.
We met so many beautiful, creative, bright and happy people, that no matter what mood your wife arrives in she will almost instantly break into the groove. Huge smiling grins become automatic. There's so much to do, or not do, if you prefer, that there will most definitely be stuff for her to be attracted to. Fun, sun, food, yoga, spa experience, mani/pedi, gambling, shopping, drinking, reading, solitude, deep thought, chi gun, sleep, coffee on the balcony, deep conversations, light conversations, bowling, swimming, beaches, hot tub or doing nothing at all - just figure out what she enjoys and it'll be there. And a week away from the kids is just a bonus.
We'll be in room 13097 - Michael and Aliza, so stop on by and say hello.