I have to agree with Graybeard. The PF9 is a really great pistol, and especially for the price. My PF9 is my primary CCW, and my wife enjoys shooting it whenever we go out.
With that said.... I would suggest you keep in mind who you are buying the pistol for. What YOU like, and want her to like, could be quite different from what she is comfortable with. You are doing her a disservice if you don't take her to a gun shop to handle a few different guns. If she already has in her head that she is going to be scared of anything more than a 22, you won't be able to break her of that by buying her anything else.
Find a gun shop (or fellow shooter) near you who has something else she can shoot....and WANTS to shoot. Sounds to me like the idea of recoil is her biggest enemy at this point. If you get a chance to have her shoot a 38 revolver (something comparable to a S&W 686 with a 4 or 6 inch barrel), she might realize she doesn't need to be scared. They still have that intimidation factor with looks alone, but the recoil is much more manageable than any of the smaller pistols.
Just my opinion of course.....but it worked for me when I got my 3 nieces started out.