I've been shooting various styles of firearms since I was a little girl.
I listen to my husband better than anyone else on Earth.
He still knows better than to buy a pistol for me unless I've tried it out myself.
Finding the most comfortable combination of pistol, grip, & ammo will be most expedient if she takes up with some local ladies after a match for show & tell & shoot. Ask ahead of time and most people will come prepared with various things for her to try out in addition to their regular match guns. I've seen felt recoil & long guns not cut to size run off more ladies than any other equipment issues, so be prepared to not only buy what is comfortable for her, but also to finesse things as she goes. I guarantee you there will be ladies happy to share their experiences with her and help her try things out with no pressure.
My main match cowboy pistols are Ruger Bisley Vaqueros in 38 spl with 125 gn TC bullets. I have small hands, but these were and still are the most comfortable for me to shoot two handed. We reload ammo, so that helps, too. When I shoot black powder it's even more comfortable...and funner.
More than anything, enjoy spending time together in an exciting hobby!