i had the same issue with my live-in partner for 2 years now when i talked to her about my recent decision to get a handgun...
a lot of good points were made in this thread and like what most of the guys are saying..
(a) educate her on gun and gun safety
(b) take her out on the range and have her actually shoot a handgun
some tips on the range:
make it fun but all the time safe
shoot a smaller caliber and at a relatively close range (she'll lighten up when she's hitting the targets)
be supportive and compliment her on her shooting skills
stay away from silhouette targets so she does not associate guns with shooting people
take her out to dinner after the range (close on a really good note)
(c) women are more emotional while men tend to be more logical.
we see a handgun for what it is --- an awesome piece of engineering that also nurtures our basic instinct -- survival and protection..
while women (or some of them) tend to see a handgun as a means for promoting violence... (I'm from CA and I know we get crap for owning one!)
so try to steer the conversation on gun ownership away from the "media hype" and towards the values of gun ownership...
-definitely buy a gun safe (go as far as sharing the combination/key with her)
-keep a minimum amount of ammunition and loaded mags inside the house
-make it a point to bring her to the range regularly when you shoot as it helps to sell it to her "as an activity that both of you can do together -- QUALITY TIME"
-make her a part of the process -- go out and get a "his and hers" kind of thing...heck -- PINK MAGAZINES JUST FOR HER!!! (maybe a bit extreme but you get the point?)...shirts are the easiest and she'll be like putty in your hands afterwards...
Hope this helps....! My lady is a tough cookie but I eventually made her see the value of "my owning a gun" and she now always comes to me when I shoot (well at least to the trap range until my g34 comes in in about 2 weeks!)...