Personally I wouldn't GAF. If his wife can legally buy the gun and the FFL is selling it to her, then why is that your problem? If I sell a gun to a dude through the legal route, he passes the background stuff, the FFL transfers the gun to him, he then goes on a killing spree. How is that my fault, or even the FFL's? Once the FFL has possession and legally transfers the gun to someone, it's on his head at that point not yours. Just my .02.