I was sitting in a room with my daughter and her friends when a Cialis commercial came on showing an older couple clearly thinking about sex. "OK, I don't need to look at that," said one of the 20-somethings. I laughed uproariously, until I realized that those people in the ad were my age.

Hope Springs, now in theaters, explores how one maintains a decades-old marriage, including a decent sex life, when mutual attraction can no longer be taken for granted.

In researching my book, I asked men about performance issues. What happens in your head when you can't get it up? How does it become (as I've heard it can be) a self-perpetuating problem? I'm close to literally a dozen fine, garrulous older men. But when I broached this topic, every one of them turned red and stammered and then was struck mute.