With all the encouragement to not dismiss bigger calibers, I thought I'd throw in a word.
Sounds like neither of you have ever shot a handgun. So the advice here is to rent a gun at a range that has them, and start with the 9mm. Or maybe even a .22 just to learn on, then go to a 9mm.
After you have been shooting a while, you'll wonder why you ever doubted that you could handle a 9mm, or a .45 for that matter.
But, since this is your first experience, the two of you need to rent a lot of different guns, take notes, stick with .22, .380 ACP, and 9mm to start.
Tell the range master this is your first time and ask him/her to go over safety and handling the gun before you get on the range.
Have her practice racking the slide while the gun is empty. It takes women practice to get down the technique at first. Plus, new guns are usually harder to rack than guns that have been run awhile.
Don't forget to look at revolvers. They tend to be the easiest to learn how to shoot on. Don't start with a snub-nose, you won't like the experience, as there isn't enough weight to absorb the recoil when you're new.
When you get ready to buy, don't sweat it. It will only be your first gun, not your only gun.
When you go to shoot, if you shoot at an indoor range, wear double hearing protection - ear plugs and ear muffs. This will help make the experience a bit more pleasurable for both of you. Indoor ranges are louder than outdoor ranges, and the noise will turn some folks off if they aren't properly prepared.
Good luck in doing your research. And have loads of fun!
Never argue with drunks or crazy people.