Valerie realized that sex was wrecking her life right around the time her second marriage disintegrated. At 30, and employed as a human-resources administrator in Phoenix, she had serially cheated on both her husbands—often with their subordinates and co-workers—logging anonymous hookups in fast-food-restaurant bathrooms, affairs with married men, and one-night stands too numerous to count. But Valerie couldn’t stop. Not even after one man’s wife aimed a shotgun at her head while catching them in flagrante delicto. Valerie called phone-sex chat lines and pored over online pornography, masturbating so compulsively that it wasn’t uncommon for her to choose her vibrator over going to work. She craved public exhibitionism, too, particularly at strip clubs, and even accepted money in exchange for sex—not out of financial necessity but for the illicit rush such acts gave her.