Re: Recommendations on a rifle for my wife..
There are different varieties of 20 gauge shotguns. A single shot with 3" duck and goose load will give you a jolt about equal to a 7RM. A pump is a little better, and a semi is sweet.
My experience, be it male or female, is all in the attitude. I knew a gal who was maybe 120, med to slight frame who shot and hunted with a 7RM. When she told me that, I said, "really???" (because after 20 rounds of 7RM on the bench, I was done for the day), and she looked at me like why would I ask that, and said 'yes'. Her dad was an avid outdoorsman and she no doubt had good education and training.
I think the comments about fit are all right on. A lot of good suggestions on chamberings, and I would say she would probably be very happy with a 25-06 or 270 which are fine deer cartridges. And if LR was in the plan, go for the 270 WSM with good fit and a good recoil pad.