It's quite simple. You need one of each caliber
. Rimfire to learn and practice with, a centerfire to get used to shooting, and a large caliber to actually use for self and home defense.
Tell her you'll need a .22 semi-auto and revolver to become proficient with handguns. Tell her you need to have a .32ACP or .380ACP for her to use - if she's of the smaller build. You will need a both a .44 revolver and a .45, because all the smaller calibers are worthless when it comes to self defense. Then you'll need to branch out into long guns. Start out with a plain pump shotgun. These are considered necessities, not even a real gun. No one can complain about having a plain ol shotty.
Once you convince her of the true need of the long gun, she will come to the realization that you do
need a milsurp in the venerable 30-06 caliber. Of course, you'll need that scoped rifle for possible hunting situations if the econmy goes bad. And don't forget the classic American lever gun. No one gets scared of a lever gun. Next thing you know, you'll have everything you're interested in.
Now, you might lose out on some sex as a bit of pushback while trying this technique, but you just need to decide what your priorities are....