"Is sending a heart in a Facebook message being unfaithful? Or is it micro-cheating?"
Other actions that can be considered micro-cheating include frequently checking someone's Instagram, messaging someone without your partner's knowledge, adding a former lover on the messaging site Snapchat, or tagging someone in a post as part of an inside joke.
"Secrecy or covert communications are often, but not always, a sign of micro-cheating," Graff says.
A study published by Monica Whitty, another British cyber-psychologist, found that sharing emotional and intimate information with another person online elicited higher ratings for judgments of infidelity than viewing pornography.
Critics of the term micro-cheating say that the concept encourages controlling behaviour and the surveillance of online communications.
"Melanie Schilling, an Australian psychologist, told The Huffington Post: "Allowing micro-cheating to continue can set up a relationship pattern that undermines you and enables your partner to have their cake and eat it too."