I see a changing landscape in which the emphasis is less on the sex than it is on the openness and intimacy and the revelation of secrets,” said Dr. Pittman, the author of “Private Lies: Infidelity and the Betrayal of Intimacy” (Norton, 1990). “Everybody talks by cellphone and the relationship evolves because you become increasingly distant from whomever you lie to, and you become increasingly close to whomever you tell the truth to.