The Signifier and the Signified, or in modern parlance, the difference between an online avatar vs an actual person.
Social media is based on a premise of underlying honesty, and yet it also gives freedom for pretend and role playing. If both parties aren't in on the game, or joke, someone gets seriously hurt.
Online dating sites and apps like Snapchat and Instagram give a version of a person to the public, to view, to relate to, and to believe. But is it an adequate substitute? Is it an idealization? Is it a vain source of hope for the truly alone and broken-hearted? Is it a cheat?