Others view it as an unfortunate inevitability, or even a force for eventual good. “In some cases, cheating might actually help to improve a relationship because it makes couples deal with their problems,” says psychologist Mairead Molloy. “Sometimes the relationship that comes out is stronger, more honest and deeper than the one that existed before because people finally step up to open communication.”

Whatever the societal perspective, cheating persists. As Perel notes: “Despite its widespread denunciation, infidelity has a tenacity that marriage can only envy.” And the underlying issue remains: cheating involves a betrayal of trust, a deception that we fundamentally abhor. But understanding it, and perhaps exploring new definitions of it, does not mean justifying it in its traditional guise.

“We are serial monogamists and adultery is part of our mating repertoire,” argues doctoral relationship researcher Limor Gottlieb. “The problem with it is deceit. That’s why many couples today choose to be in CNM (consensual non-monogamous) relationships. Research shows that CNM couples are much better communicators and their relationships are built on honesty and respect.”

While CNM may not be for everyone, the ideal of clear boundaries should be. And while we may never be able to truly ‘relax’ about infidelity, our willingness to consider different kinds of romantic relationships – or draw inspiration from those who do – may make communication within them clearer.

Ask anyone if they’re relaxed about cheating and they’re likely to say no. But in an era that appears to be swinging back to a less puritanical outlook, the line they take will be based upon their own more nuanced understanding. Expressing that understanding clearly to a partner (or partners) is the key.

Wait, is cheating not a big deal now?