Sadly, many men don't realize the profound effects infidelity can have on the emotional life of a trusting long-term partner. Inevitably, most cheaters are eventually found out, and the resulting fallout is often much greater than anticipated by the cheater.
Why are so many men acting badly? The easy answer is to just say that these men are high-testosterone-driven cheaters. But as a neuroscientist, I know the brain tells a different story.