A small group of people are totally enthralled by aviation, and the idea of leaving earth.
My experience has been that a vast majority have feelings about the hole thing, which range from ambivilence, to down right hostility. You can't change that. Perhaps your wife will grow you appreciate aviation, but beware that pressing it, could make it worse. If negative experiences are expected, that will be the percetion, and it's really easy to perceive aviation negatively, if that's what you are expecting.
Hopefully you can plan a trip which is so certain of success, that it will serve to demonstrate the fun, without the fear. Do not demonstrate steep turns to her!
Try for an aviation based social event to go to together. Particularly, if she can meet other wives, ideally happy flying wives. Ideal would be to team up with another pilot, who is extremely confident with his four place aircraft, take your wife on a two couple's trip. The other more experienced wife might help her to see the fun in the whole endevour. Take care though that nothing goes wrong. The negative can be worse that the postive very easily....
Prepare yourself that flying just may never be something she embraces. Let her know that she is entitled to her opinion, if you're entitled to yours, that may be the best you can hope for!