How important is sex in a meaningful, intimate, and committed relationship? What happens when a couple no longer wants to have sex with each other? What if sex disappears from a relationship, after two years, or ten years, or forty years? What happens if one person is less able to have sex-maybe because of a health condition, or a physical accident - or becomes less attracted to the other because of a physical change (e.g., gaining or losing weight), or simply because their desire has changed? Does one person have the ability to regulate the sexual activities and desires of another person?