Even if your wife doesn't have an interest in riding (which is a heck of a lot better than having an objection to riding), I'm sure she has an interest in other things that you can get to while riding. I mean, you can take her to fun places on the bike, get great food, ride on beautiful scenic roads that are normally unappreciated in a car but suddenly become alive when on a motorcycle (somewhere that has great smells - the salty ocean air, citrus trees in bloom, countrysides that smell of green pastures).
Also, you might take her to places where she can experience the comraderie with other riders. It's always fun to feel like you are a part of something, one of the gang. It's fun to get the waves and nods from other riders, or a friendly hello at a nearby cafe from a fellow biker that would normally have just been another stranger passing by.
I don't have much else to add, other than if she doesn't get into the ride, that's ok. But you can help her enjoy the destinations and the other aspects of the experience. Of course, I'm sure you already ride conservatively when she is with you, and you instill a feeling of safety and confidence, right?
Good luck. Maybe she just needs a really hot new riding jacket and matching chaps!
One can never consent to creep when one feels the urge to soar - Helen Keller