He'll confide in her if she sympathizes with him and expresses interest. Same with you. Take the guy out shooting, talk guns, etc etc etc. If he's lost it he'll eventually confide in another gun nut. Most likely he finally discovered that it's great fun.
Another possibility is the stress of the world. When I'm nervous about things I become more of a gun guy. My girlfriend can tell when I'm low on money because I clean my guns all the time. Some primal instinct to protect myself, even though it doesn't make logical sense.