It looks like she doesn't want to touch it, like she doesn't want to get down into the gun. Is she leery of getting punched in the cheek or or the sticky plastic? She definitely needs to get closer to the stock and the scope, but I'm not sure how you convince her of that. The buttpad is in a good spot, she's not doing that wrong she just needs to get a lot closer. She also needs a much higher comb one way or another, her cheek is higher and thinner than yours.
I think you're onto something with having a neutral third party teach her if she wants to learn. One spouse teaching another to shoot is about like getting a canoe or a manual car or a tandem bike, kind of a divorce recipe for lots of otherwise rock solid couples. Can love each other a lot but not have the recipe for teaching something new to someone who's probably a little competitive with you. It took two years of coaxing, extremely zipped lips, and a trip to the deep desert to teach my girl to drive a stick even though she rode a ninja in college. Either way you gotta find a comfort level where she can extend into the gun instead of just holding it like a camera. I'd teach her how to use a sling for support then get some practice without rests or bipods so she can learn to use her body to aim and get joined with the stock, then from there see what shape/fitment issues there are.