When I first got married, I nonchalantly brought up getting a gun. I forgot what the circumstances were, but we were talking about something, and I just said "I need to get a gun", and she said, "yea, you should". I forget the convo, but I intentionally took it in a direction where I could bring up guns. I went the next day and purchased the Glock 19. I owned one ( S&W Sigma) before when I lived with my ex gf in a not so good part of town, but sold it when we broke up and lived alone. I am more about defending others, than myself.
Anyway, at first she was hesitant of it, as in I would bring to bed side at night, and she was worried it would go off, etc. I went soon after and took the CCW class, just telling her it was a gun safety course or something. I got my permit and started carrying with out her knowing. She caught me once at a wedding when she put her arm around me, and got kind of upset I was carrying, calling me paranoid and what not. I told her we probably need the gun more out in public, than at home, stuff like that, etc. I still kept carrying, she noticed a few times and said something, until finally she just stopped saying anything. I think that she likes that I carry, but doesn't want to admit it. It has been a while since she noticed, or at least made it known she noticed, and I carry pretty much everywhere legal, except Church. I know own 3 handguns (was 4, but sold one) and a shotgun.
She was the kind of person that thought guns go off by themselves. I showed her how things work, and took her shooting and what not. She even wants me to take her little brother now. She was also all for me going to Front Sight, and becoming a member. I haven't got her to the point of carrying herself, but things take time. I believe she knows I carry, but doesn't say anything, and pretends she doesn't know. But I know there are times when she seen me put the gun back in the safe, and noticed a weird little bulge of my j-frame, when my keys and phone are in other pocket, and wallet in another.
It just takes time, show her how it works, take her shooting, she will open up. People have irrational fears, and guns is one of them. Good luck.