Falconflyer has it right. Felt recoil is a combination of many factors including the weight and the fit of the gun, the payload (shot weight) and velocity of the ammunition and the sensitivity and robustness of the shooter among other things. And these factors all interact in different ways.
Let’s start with the shooter, your wife. On the physical aspect, she is petite, most guns are made for adult males 5’8” to 5’10” at 160 to 180 pounds so for her most guns will be too heavy, be too long in the stock and large in the grip to be comfortable or easily controllable. Unless she is an athlete her muscle strength will also be considerably less than that of the average man so just raising the gun, mounting it and swinging it will likely be a struggle for her, especially because of the stock being too long and the comb too low. To her the gun will feel very heavy, clumsy and awkward. Then there is her mental attitude. In general women beginners have two main concerns and hitting the target isn’t one of them. #1. WILL IT HURT ME? #2. WILL I LOOK STUPID? #2 is easily dealt with, one on one initial instruction from a trusted, knowledgeable and patient instructor or mentor. Nobody else except perhaps yourself nearby.
#2 is where it gets complicated. Gun weight and shot weight & velocity have the most effect on kinetic recoil. Gun fit and to a lesser extent the length of time of the recoil pulse have the most effect on felt recoil. Remember, a poor gun mount will always produce more felt recoil, mount and stance are important.
So a heavier gun with a light load looks like the solution? Half right. Light loads yes, but if your wife is typical for her size and fitness level she will find a heavy gun too hard to mount and swing, nearly impossible if the stock is too long or the gun has forward weight bias for her because her arms will be stretched out. Ideally you can beg, borrow or buy a short stocked well balanced gun with small grips, then go with the lightest loads that you can find. Keep the gun on the lighter side, she won’t have the muscle strength to handle a 8 1/2 - 9 pound trap gun. This base will make the most felt difference but gas autoloaders, stock recoil reducers and even porting can build on this base.