Unless your GF is an experienced shooter, I'd say neither.
I've owned a couple J-frame .38's and they can be an acquired taste. Good guns but for a good long while I (a 200+pound 5'10" man who's been shooting for over 20 years) was only good for about 40 rounds before the recoil started to get to me. I'd think that just one or two rounds from one may be enough to talk a new shooter out of ever picking up a gun again unless you were introducing them with very mild loads.
I totally second the idea of several trips to the range and some gunstores to let your GF figure out what she likes.
I sense that you have the best of intentions here but you really are going to have to just sort of set her loose on this.
Your only interaction should be things like "Can you work the slide?", "That's overpriced by $50.", Or the occasional "Jennings?!!! PUT THAT BACK IN THE CASE BEFORE YOU BREAK IT!"
Over the course of a year or so I had my GF (now my ex) to the range with every gun I owned and every one I could borrow for her to try out.
To make a long story short, she was a total newbie the first time we went to the range. She tried everything I owned along with every handgun I could borrow for her to try.
We went to a few gun stores for her to handle guns.
Even with very little experience she was able to decide what handled well for her and what didn't and what fit her hand well.
Ultimately, she bought a Walther P-22. My brother and I helped break it in and zero the sights with her and make sure she could use it but it was her choice from start to finish.
It is underpowered.
But it's pleasant for her to shoot so she probably will.
Ammo is cheap and she still needs a lot of practice.
It fits her hand well and she can work the slide and all controls without struggling.
The controls are ambidextrious - she's left handed so this matters.
It's small and light enough that she can stick it in her purse when she decides to get her permit.
I tested it for her to ensure that it's reliable. It is. I'd carry it.
It's not the hammer of Thor, but loaded with some hot CCI solids, it is at least something.
Maybe not the ideal choice but she's a whole lot better protected now that she has her own gun than she was a month ago when she had no guns...