We’ve all had that friend ― the one who can make you laugh and celebrate your wins, but also slip in stinging comments and backhanded compliments. It’s the kind of person who blurs the line between friend and foe, i.e. the “frenemy.”

“The term frenemy describes someone who is ostensibly a friend, but someone with whom you have a one-sided or unbalanced friendship that is inherently painful and unsatisfying,” psychologist and friendship expert Irene S. Levine told HuffPost. “The person pretends to be a friend and may actually believe they are, but their behaviour is more characteristic of an enemy. The person may be undercutting, insincere, unreliable or take advantage of you.”

Unlike genuine friendships, these kinds of relationships involve fake closeness, bad intentions, secret competition, undermining behaviour and negative talk behind your back.

“These relationships often create stress instead of comfort,” said psychologist Stefanie Mazer. “It’s hard to build trust with someone who is a ‘frenemy.’ These relationships can be harmful to your mental health. Most of the time, it’s better to step back and put energy into people who are genuine and have your best interest at heart.”

Still, despite the toxicity, many people struggle to let go of frenemies. Below, experts break down the reasons why you might be holding onto these tricky relationships ― and what it says about you.

1. You have a long shared history.

“People are reluctant to give up long-term friendships, even with frenemies,” Levine said. “These people may not have always been frenemies, and they may have shared many enjoyable experiences with them. Thus, they tend to forgive and overlook.”

The mix of negative and positive can make it challenging to truly cut ties.

“There might be a history of them being pleasant with you, being there for you, sharing resources with you in some situations,” said Danielle Bayard Jackson, a friendship educator and author of the forthcoming book “Fighting for Our Friendships: The Science and Art of Conflict and Connection in Women’s Relationships.”

“You likely do have moments from your relationship where this person genuinely offered emotional support,” she added. “The positive memories and shared history are, in my........

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