It took me a while to work up the courage to tell my wife, Nora, how much it turned me on to imagine her with other guys. I never really knew myself until one otherwise unassuming day when she offhandedly pointed out a guy in a restaurant as someone she had previously dated. I had feigned shock when she said it and suggested we leave immediately, abandoning our burgers and fries mid-meal in embarrassment. But she just rol...