This heightened ethical sensitivity is being applied to sexual intercourse, an activity whose standards have long been mutable and often lax. My mother’s generation, coming of age in the 1970s, imagined that when a woman went to a man’s apartment, she’d signaled her intent to have intercourse. Twenty years later, I thought I could walk out of that apartment without even an obligatory kiss, but I would never have lain down on a mattress with someone with whom I didn’t plan to hook up. Today, inviting someone into your bed is “cuddling,” usually but not always sexual, and certainly does not have to lead to intercourse.