Ok... having been through this with the wife and mom-in-law already, I THINK I'm qualified to answer...
The correct gun to get your SO is WHICHEVER GUN SHE WANTS. When I first met my wife, the only handgun I had was my Colt 1991 Compact, and she HATES it: doesn't feel right in her hand, etc. So we played around with several, and ended up getting her an H&K USP 40c... which has since been sold to a friend. Why? Wife decided she LOVED the feel of a Kimber (and she'll be getting hers in the next week or so)...
Mom-in-law was an even funnier story. Took her out to teach her the basics. She liked the Ruger Std... wasn't too thrilled with the 9mm... and I almost had to cold-cock her to get the 45 back! And the looks I got when the guys at the range found out it was my mom-in-law I was teaching were PRICELESS...