The fatal flaw theory will make or break all your friendships.

Fatal flaws are often things we see in storytelling, particularly in Greek tragedies.

But what if they're manifesting in our own everyday lives, too?

Well, maybe not in quite such a dramatic fashion, but it's true that most of us have at least one trait that isn't doing us any favours.

TikTok is full of mind-blowing theories about love, dating and friendship that will have you re-evaluating all of the behavioural patterns you didn't even know you had — for better or for worse.

One friendship theory that's become particularly popular on the app is the "fatal flaw theory", which is supposed to teach you how to have healthier friendships. But is it actually backed by psychologists?

Watch: What type of friend are you? Post continues below.

What is the fatal flaw theory?

The "fatal flaw theory" was first coined by TikTok user Tinx, who said it is based on advice her mother gave her while she was complaining about a friend's annoying habit. She said the friend was a compulsive liar, and it was something she'd rant about to her mum all the time — until her mum told her enough was enough.

Basically, the theory (which is really more of a rule) states that everyone (yes, even you) has a "fatal flaw" or trait that someone will find frustrating or annoying — this could be always being late, being a terrible texter, exaggerating stories, being a conversational narcissist, etc.

The rule is, if you love the friend and appreciate them in your life, then you should accept the flaw, let that irritation go, and stop complaining about it to other people. Love them as they are, and be a good and loyal friend.

However, if you can't get over or move past the flaw, then maybe it's fatal to your friendship and you should take a step back and re-evaluate the relationship, rather than bitching about it behind your friend's back.

@tinx

#answer to @3margaretb game changer

♬ original sound - Tinx

The advice has been praised by other users on TikTok as being "life changing" when it comes to helping them appreciate their friendships. One TikTok user described it as having "saved" her from "a lot of stress and frustrations towards people". Another said it's made navigating difficult friendships so much easier.

@emmaaroof

explaining the ‘fatal flaw’ theory✨🫢🫶🏼 lmk what fatal flaws you struggle with!! #fatalflawtheory #relationshipadvice #friendshipadvice #postgradlife #awkwardconversations

♬ original sound - emma roof

What do psychologists think of the fatal flaw theory?

While the fatal flaw theory is clearly helping people online, what do experts think of this rule?

Principal psychologist at Enriching Lives Psychology Carly Dober told Mamamia that while she thinks it's a helpful tool that encourages affection in our friendships, she does have some conflicted feelings about it.

"I think it's true that we all have weaknesses or things that might be a bit undesirable to other people. If people can accept that in us, that can be a lovely state to be in, because no human is perfect," she said.

However, she warned that the fatal flaw theory could be misconstrued to make people feel like they have to be accepting of behaviours that are actually harmful — so we should be careful about when and how we use it.

"A flaw that is relatively harmless is someone being late. It can be annoying if it happens chronically and you have tickets, or you're excited to go somewhere," she said.

"But if someone is being psychologically abusive or emotionally manipulative, it's a different story."

@saymoretherapy

The #fatalfriendflawtheory is just a fun way of having empathy and loving people for their imperfections. Nobody is perfect! #friendship #communicationskills #makingfriends

♬ original sound - Cat ✿ Therapist

Dober warned that the fatal flaw theory could be weaponised by people who might want to continue a harmful behaviour without being held accountable. They might try to set a standard or expect people to put up with a behaviour that is not okay, or use the theory to justify not changing their behaviour, because you should accept them as they are.

It's with this in mind that it's important to know what we mean by a "flaw" — Dober would expect this to be something like a person who is always forgetting to text back or who never pays for the Uber; NOT someone who is cruel or abusive to you.

If you're unsure about whether someone's "flaw" is hurtful to you or not, she recommends speaking to a trusted friend or family member to give you some perspective.

Otherwise, though, she ultimately reckons the fatal flaw friend theory is a good empathy tool. At the end of the day, it reminds us that, most of the time, we love our friends more than they annoy us. And that's what really matters, right?

Feature image: TikTok @hanli.hoefer; @emmaaroof.