The 'occasion theory' is the key to working out if your partner is a narcissist.

Have you ever been so excited about a big event that you meticulously plan out all the details — what you'll wear, how you'll do your makeup, how you'll get there — only to find yourself completely miserable when the occasion rolls around?

According to Bella Bennett, a South Australian content creator, there might be more to it than a simple case of cold feet — especially if you've mentioned said excitement to your partner.

Bennett believes this could be the sign a narcissist has taken root in your life.

Recently, Bennett's "occasion theory" went viral on TikTok. In the video, she said that theory is an easy way to identify the early red flags of a toxic relationship.

Watch what Bella had to say about the occasion theory. Post continues after video.

@bellastalktime Special occasions ✋ . . . #toxicrelationship #narcissism #redflag ♬ original sound - bella

"[The] quickest way to find out if you're dating a narcissist is when you have a special occasion coming up, whether it's your friend's birthday, whatever; make it anything, make it up," Bennett said.

"Watch how they treat you [in] the days, the nights, the morning, leading up to that occasion.

"The moment something else is making you happy, and the attention is going off of them, they can't stand it."

'It just brings out that pathological envy'.

Nova Gibson, director and founder of Brighter Outlook Narcissistic Abuse Counselling Service and author of Fake Love: Understanding and Healing from Narcissistic Abuse, said that events are powerful triggers for narcissistic behaviour.

"It's absolutely textbook for a narcissist to ruin any special occasion, any event, because they want to isolate you," she told Mamamia.

"They don't want you finding happiness or joy in anything other than their company.

"It just brings out that pathological envy."

The strategies a narcissist will use to ruin an event can vary, Gibson said.

"If they are going with you, they will start an argument, or just very covertly make you feel bad, normally right before you get out of the cab, so you have an absolutely miserable time, and they will be the life of the party," she said.

"Narcissists will always ruin a holiday, Christmas, birthdays and, of course, special events.

"And if you're going out on your own, well, they will ring you every two seconds, they will get sick, make you feel bad."

The types of narcissists and their tactics.

Gibson said that broadly, narcissists can be categorised into two types: covert and overt. The vast majority — in her opinion — fall into the covert category. But when it comes to relationships, the abuse and tactics used by narcissists are generally universal.

"They use the same strategies to hook you in, get you trauma-bonded, addicted to the relationship, to dismantle your personality and make you completely dependent on them," she said.

So, what should you look out for?

One of the earliest red flags is love-bombing, but that can be hard to identify in the fresh throes of dating, "because it feels good".

"At this time, all the dopamine receptors are being hit at once and all the happy hormones such as oxytocin are flowing in abundance," Nova said.

Then, once you're bonded, the devaluation stage will start.

"You won't pick it immediately, but when the devaluation starts, that's when the red flags will be really small," Gibson said.

Perhaps they sulk at an event, or a comment about your appearance or outfit. But as Gibson said, "the next time, the red flag will get a little bigger and brighter."

Red flags and feelings that shouldn't be ignored, according to Gibson, include:

• The sense of moving too fast — a whirlwind beginning.

• Feeling like you've met your soulmate.

• Talking about a crazy ex, or badly about an ex in general.

• Talking all about themselves.

• Oversharing too much too soon.

• Then, expecting you to open up.

• Strange behaviour leading up to events.

• And the screeching halt: This is when the love-bombing ends, and typically comes when someone is "addicted to the feeling of being their soulmate."

The last stage, Gibson said, is a big red flag that normally happens when people are already trauma-bonded to the narcissist. At this point, the common emotions felt will be confusion and a sense that you're with Dr Jekyll and Mr Hyde.

"That is an act. That person doesn't exist, and you will never get that person back," she said.

Learn more signs that could indicate you're dating a narcissist. Post continues after video.

So how do you end a relationship with a narcissist?

It's not an easy process.

"You don't end it, you escape — you don't break-up with a narcissist," Nova said.

"The ending will be horrific because they want to be planted in your brain forevermore… they don't want you to stop thinking about them, so they will come back and do what we call 'hoover you', which means to suck you back in.

"If you can get away, the hardest part is to go no contact."

Feature Image: Getty.