1) Buy a small, non-intimating bike for her.
. This not a ploy for you to get another bike, it is truly, a "her"bike. She needs to have buy in on the bike, and it needs to ergonomically fit her (not on her tippy toes) and low weight. This bike should honestly be badged a beginner bike. You probably won't own the bike forever, but the bike should be pleasant enough to grace your garage for a year or two until she decides she has outgrown it. Next buy some little cones, 15-20. Set them up at the local high school parking lot on the weekends, and just let her ride.
2) If all goes well with 1), then late summer back to MSF she goes. Look for one that has a published low student to instructor ratio:
TRA 8300 Personalized Basic Rider Course - $350
Exactly the same course as the Basic Rider Course except that the class size is limited to six students. The ratio is 2 instructors to 6 students in the Personalized BRC, versus 2 instructors to a maximum of 12 students in the regular BRC. Some students are more comfortable in a smaller class size environment in which to learn.
This article might help too: How to get a girlfriend to ride a motorcycle: 7 tips for getting your girl to ride and love it, on her own bike