ALL RELATIONSHIPS—LOVERS, PALS, the chick behind the counter at Starbucks—at some point involve conflict. Yet here’s what’s odd: In school, we learned so much—the periodic table, algebra, how to make a baking soda volcano—but never how to argue.

So we carry on like kids: “I’m taking my toys and going home!” It leads to breakups, bruised feelings, ruined friendships.