May I kindly and politely suggest you re-think this?
Whatever firearm she likes the best and shoots the best is going to be most effective for her.
The trade-offs between size/power of the cartridge, vs. size and weight of the firearm, vs. shootability, vs. round capacity can be mixed and combined into thousands of different firearms - and that's for a reason. What is the best answer depends on a lot of personal factors. Her "best trade off" is probably going to be different than yours.
I agree with you that there is a major drop off in performance when you go less than 9x19 but there still may be other factors in the decision that make that the right gun for her. Lots of very smart people and very good shooters carry .32's and .380's etc. They have their reasons. Your wife may be one of them someday.
My current wife is from Mass. all that she carries is attitude. Dislikes guns. She was also raped in college. How brainwashed are these Yankees? I have no comprehension.
My wife and I carry Ruger SP-101 .357 revolvers.
She carries in her pocket book or in a shoulder rig. Sometimes both ways.
I carry on my belt in the summer and in a should rig in the winter.
Each of us have 3 SP-101's.
This wife carries a Sig P-239 with Crimson Trace laser grips.
Prior to that, carried a S&W 3913LS until the desire to add laser grips caused the need for something else.
If the recoil of 9mm seems too much for your wife, it may just be a matter of practice and working on grip technique and stance. Lots of good info at the following site:
Having recently had a pleasant experience with a Glock 17, am hoping to add a Glock 26 to the above soon.
I have previously not been fond of revolvers, but the Ruger SP-101 in .327 is changing that.
My wife carries a Bersa Thunder .380. The stopping power of the .380 is at the bottom of my "man stoppers" list, but it is on there. A good JHP .380 is very effective. A hit with a .22 beats a miss with a .50 BMG every time.
This'll sound weird but my girlfriend is carrying a 90 year old revolver made by US Revolver Co, which was the Iver Johnson store brand. It's a tiny five shot, double actiom, break open revolver chambered in .32 S&W.
We both went and got our carry permits together and, since then, it's been tough to get her to actually carry. I had that old revolver, showed it to her and she was comfortable shooting it at the range. So, I figured something was better than nothing. It'll at least be a forceful "get off me," if necessary. It's actually a pretty cool, dependable, simple little gun. I'll keep nudging her towards something a bit more powerful but, until then, at least she has it with her most of the time.
Initially, after trying my P239 and renting a couple of others at the range, we got her a S&W 442, but after she shot it more realized she didn't really like it. She also couldn't really hit well with it at the range. We rented the P9, and she really liked it as well as being much more accurate with it, so we went ahead with purchasing one.
Just make sure she gets her say in what she carries, but it sure helps if she can try it out on the range also.
Well, at least I like to carry the 442, but I couldn't talk her into the 642 when it was gonna be her gun Then she gets the stainless Kahr because it looks nicer in stainless.