Really, really recommend she do the course (and it'd be even better for her cause you'd be there too). If she's worried about being the only girl there, well that's probably not going to be an issue and she'll become too busy learning to worry about that for long. (Besides, how often can she go to a class that's usually made up of a majority of men around her...
Do you have a bike already and are you prepared not to freak a bit if she drops it? Does she even fit your bike comfortably? If you are new to riding as well, then its not a great idea either - she should most definitely take a course.
While I was on my course, our group and instructors spent a bit of
time watching this guy in the parking lot across the street of all places!
showing his wife/gf how to pilot his beautiful heavy-looking cruiser (I was too noob to know what type bike it was) and we all had to collectively groan when she dropped it at least twice while we were watching.
Know anyone that taught someone or learned to drive a standard shift car using the "teacher's" car? Some of those are not pleasant experiences - like lending out your toothbrush for some. Go for the course - won't cause unneccessary stress on your relationship either.