I always hate to be that guy, but the sad truth is that a SAK is usually the safest option if you don't want the knife to permanently end up in a drawer. This is also of course if she really has been nagging on you about how much she wants a knife in the first place.
You asking her 5 times and she answering "I don't know" 4 times and "Yes" one time doesn't count . Then you're probably better off getting her something else that you know she will like.
Truthfully, I would recommend not getting any frame lock, liner lock, or assisted opening knife for your wife if she plans to carry it in her purse. My wife will simply not have one because she has had two come open on her and she was nearly injured. I have had Leeks come open in my pocket and I switched to a Spyderco Caly3 instead. A good back lock has a bias to close and so does a Caged Ball Bearing Lock, but a bit less than the back lock. I would recommend the orange Delica. However, the Cold Steel Finn Wolf is less than $38.
Spyderco Delica, 2.95" blade. This is a slim, easy to carry, safe knife.
My wife carries a dragonfly H1 in her purse. It's a great knife for people who don't regularly carry knives. I also put a blue sak cadet on her keychain. She uses the scissors and tweezers way more than either blade.
I'd recommend the Mini Grip. But my true advice is to show her all the suggestions on here preferably in store if possible or at least online and let her choose her own. There's not one knife that works for everyone obviously, so let her pick her own.
Dragonfly, Delica, Roadie (no lock), somebody else mentioned the Meerkat, CRKT Pilar is out in orange now, Boker Magnum, Cold Steel Mini Tuff Lite. My advice to husbands getting knives for the wife's is to take them to a place they can get their hands on them and get out of the way.
Reminds me of the guy whose mom needed a riding lawnmower. He did all sorts of research on motors, transmissions, decks and other features, and then took his mom out to look at the ones he had determined were best.
They pulled up to the first mower dealership and, while still in the car, his mom pointed at one and said "I want that one." When he asked her why, she said she thought it was cute.