As long as there have been committed couples, there has been infidelity. Broken vows of sexual exclusivity is a recurring theme in Greek tragedy, the Bible, medieval literature, Shakespeare, and the modern tales of Alfred Hitchcock, Frank Sinatra, and Taylor Swift.

Survey data regarding cheating keeps changing as social definitions of cheating evolve. And the invention of cars, telephones, and the internet—not to mention mixed-gender schools and workplaces—have multiplied people’s opportunities for a broader range of physical and emotional relationships.

Infidelity is one of the top reasons people see a therapist, either alone or with a partner. Most people think they know something about infidelity as a general subject, but when it actually occurs in someone’s life, they need to shed any common myths about it quickly.