My earlier answer seems to have vanished into cyberspace, so here it is again.
As far as multiple weapons, it depends what state you are in. In Missouri there is no limitation.
In reguard to your girlfriend, you should not choose a handgun for her. It doesn't matter what you or I like, if it doesn't fit her hand properly, if she doesn't understand how to operate it, if she is not trained to use it safely, or if she just doesn't like it, it's the wrong gun. On top of that she (and anyone else) should have some training in the defensive use of weapons. As the answer above stated, try and get her to a range that rents handguns, and let her try a few out to see which ones fit her and she can operate safely. If you don't have a shooting range nearby that rents, maybe you can get a small group of friends that shoot, to join you, and let her try some of theirs. Hope that this was helpful. And always remember, Safety First !
Karl
Keep your finger out of the trigger guard, until you are on target and ready to shoot! Always Remember, Safety First! MoShootingStar.com