I'm a newbie female gun owner myself, with a supportive and loving boyfriend who is a font of information.
If you can try to take a back seat in the conversations as much as humanly possible and let her drive, it will be of great benefit to her. Be there as a resource, not as an instructor. If she can feel comfortable going to you for information as frequently and as in-depth as she needs at any given time, she'll find it that much easier to return to the topic (either through you or under her own steam with other resources available) just as often as the idea pops into her head.
What someone earlier said about finding formal instruction outside the home, I'll add my +1. Also a +1 on what Ride4theBrand said about situational awareness and getting her to watch your 6 as it were. The biggest change, for me, hasn't been the educating myself about guns and calibers. Or the actual shopping for a gun. It has been the regular daily habit of being in Condition Orange (aka not running around in Condition White = Totally Oblivious state).
The whole not being in condition white is, completely separate from any actual tactical or strategic self-defense or home-protection choices, probably going to be the single biggest change for your wife. For me, it has been the hardest but also perhaps the most empowering.
Scary to always think what's around that corner? yes. Disturbing to realize just how many nights you almost fell asleep without closing and locking the window? yes. Developing a pattern of "checking the perimeter" visually or physically when you leave or come home? Requires actual training. Good habits, just like bad ones, take 21 days before they are habits.
All the thinking, all the not being in Condition White, will do its job of convincing your wife in her own time and terms that really, she wants a gun. Not mace. Not a billy club. Not 21 classes in Martial Arts, but a gun. (I'm not trying to devalue the non-gun options, but as with anything all the options would require training and defense scenarios. Most likely, only the gun would actually get that treatment. Most folks just throw mace in their purse and forget it, never reading far enough to even know that an attacker could close his eyes and hold his breath and continue with the attack. And few women taking martial arts classes for self defense actual continue with regular MA training beyond a single 2 hour evening of uber-basic tactics. I'm just saying.
Anyway, what has been working for me, that my dear bf has been doing mostly very effectively, is just having him available as a resource and then using him like I do a dictionary or a Google search or any other form of information look-up: I ask pertinent questions, get my answers, sometimes go digging for more, sometimes get a whole lot of shitola that I hadn't bargained for, but mostly being a grown woman I make my own directions and my own choices on my own petard. Letting her have the freedom to do that will (I'm betting) work wonders for shortening the amount of time it will take to get her actually owning and using and potentially every-day carrying her own gun.
Just my 2c.
M-