Anna, who graduated from college three years ago, told me that in school, she struggled to “read” people. Dating apps have been a helpful crutch. “There’s just no ambiguity,” she explained. “This person is interested in me to some extent.” The problem is that the more Anna uses apps, the less she can imagine getting along without them. “I never really learned how to meet people in real life,” she said. She then proceeded to tell me about a guy she knew slightly from college, whom she’d recently bumped into a few times. She found him attractive and wanted to register her interest, but wasn’t sure how to do that outside the context of a college party. Then she remembered that she’d seen his profile on Tinder. “Maybe next time I sign in,” she said, musing aloud, “I’ll just swipe right so I don’t have to do this awkward thing and get rejected.”

The pleasure of sex arises from many factors including the release of neurochemicals such as oxytocin and dopamine, which flood the system during orgasm, as well as the sense of connection communicated by touching, massaging, and cuddling. Given the enormous variability in activities that people find arousing, there is no one way to be sexual. Men are especially stimulated by visual imagery, and about 90 percent of young men report using pornography with some regularity, often because they lack a partner or don't know how to bridge the differences in sexual appetite and interest that can occur between partners in the absence of discussion of their sexual pleasures. Many people engage in behaviors that were once perceived as atypical, such as dominance play and anal intercourse. Researchers know that flexibility in sexual repertoires is healthy and generally enhances relationships; they regard a specific behavior as problematic only when it creates harm or distress for one or both partners or when the behavior is compulsive—that is, it becomes the only means of arousal. "Sex addiction" is a label often used to suggest excessive interest in sex, but studies show it may be more related to the moral/religious environment in which a person lives.