Ownership of guns makes us safer in some way in that no one can just come and attack you because the thought of you having a gun hinders them. If it was illegal to own a gun, people would be under the mercies of those who have acquired them illegally.
That the "law-abiding citizen" always comes out the winner against the crazy / bad guy, and that nobody else gets caught in the crossfire. Yes, a person who suddenly finds themselves in a completely unexpected life threatening situation is going to able to keep their head and take out an opponent who is either mentally unstable or a professional criminal, maybe with previous experience with his weapon. I also question how many of the pro-gun types have ever been in this kind of situation where somebody pulls out a gun. The reaction is more like bloody and things get very crazy very fast, and I question how many "law-abiding citizens" are up to handling their weapon in that situation. Now that all doesn't mean I can't understand why people want to carry guns for self-defense. I question their risk-assessment skills, but I can understand the reasoning if you live in certain places. Just pointing out there are some logical fallacies at work too.
Gun ownership does not make anyone safer in and of itself. Some people may feel safer, however that is no guarantee that they will be safer in a moment of terror. There are far too many guns in the hands of criminals and mentally ill people. The amount of children killing themselves or others with their parent's guns is disgusting.
People often point to accidental evidence when they are trying to make a point that is not readily proved by facts. There are many reasons why the girlfriend was lucky and there are many factors that led to her having a gun that made her safer. Statistically, however guns do not make us safer overall. In addition to the numerous other statistics that have been recorded, it is easy to look at countries that do not have guns and see that violence and death by violence is lower in countries where guns have been banned or severely restricted.