SCIENCE: Study: Sex with Your Ex Can Be a Good Thing. “Researchers at the University of Arizona looked at post-breakup psychological adjustment and ongoing contact among 137 married adults who had recently separated. As you’d expect, people who accepted the breakup were generally better adjusted while those who still pined for it weren’t. But that’s not all: for those who didn’t accept the breakup, making a clean break (the advice everyone gives after a breakup) didn’t leave them any happier than trying to keep up a friendship. And if they stayed in touch with their exes, they were actually doing better if they kept having sex with their partner.”

So in your pre-nup, be sure to provide for post-separation sex. Which I think is the punchline from an old New Yorker cartoon.