“The most intuitive reason is that ambivalent relationships are unpredictable,” Grant writes for The New York Times. “With a clear enemy, you put up a shield when you cross paths. With a frenemy, you never know whether Dr Jekyll or Mr Hyde is going to show up.”

“I had assumed that with a neighbour or a colleague, having some positive interactions was better than all negative interactions,” he continues. “But being cheered on by the same person who cuts you down doesn’t buffer the bad feelings; it amplifies them.”

Indeed, studies have shown that a frenemy can cause you more distress than a straightforward enemy because these relationships are often so confusing that you never quite know what you’re going to get. However, research from earlier this year concluded that most of us maintain frenemyships because the benefits, such as saving face, maintaining social networks and sustaining important connections, outweigh the negative ramifications of dealing with the relationship or terminating it.

So if you are going to stay in contact with a frenemy, how should you go about it?

Ambivalent relationships: why we need to watch out for our frenemies even more than our enemies