Selena Gomez fans spark bizarre theory following Justin and Hailey Bieber’s post

Following her engagement announcement, fans of Selena Gomez have sparked a strange theory about Justin and Hailey Bieber's relationship.

If you've been any what informed about pop culture in recent years, the alleged feud between Selena and Hailey will not have passed you by.

It's rooted in the fact that there was very little time between Selena and Justin's relationship ending before he met Hailey - and some claim there was even a cross over.

Once upon a time, Selena Gomez and Justin Bieber were one of Hollywood's biggest couples (Gregg DeGuire/FilmMagic)

That is despite Hailey profusely denying that there was ever a time that Justin was dating both of them at the same time.

However, the so-called 'beef' has evolved over the years into a whole range of wild fan theories. And Selena announcing her recent engagement to producer Benny Blanco was only going to reignite the chatter.

The former Disney star posted a picture on Instagram showing off the enormous ring, along with a series of cute snaps from the joyous event.

These included a sweet picture of the happy couple hugging, and Selena's undeniable smile told fans everything they wanted to know.

But one person's subtle congratulations came as a huge shock to fans.

Selena Gomez announced her engagement on Instagram last week (Instagram/@selenagomez)

In a shocking turn of events, Hailey Bieber liked the engagement post - and fans have now sparked a new rumour that could potentially cause some tension.

It was suggested by eagle-eyed users that Justin hadn't attended his wife's recent birthday party, or even posted about it on social media. But following Selena's bombshell announcement, he has uploaded multiple snaps of the happily-married couple.

And, of course, fans are suggesting he's only done it as a result of his ex's post.

One user said: "Why do they suddenly re-appear when Selena is active on social media? It’s always like that," as another added: "Why are they so obsessed with her?"

But others actually came to the couple's defence.

The couple posted on Instagram together following Selena's announcement (Instagram/@justinbieber)

As one noted: "You guys are weird, what does Justin have to do with Selena's life? He posts his photos whenever he wants."

Another agreed, writing: "That has nothing to do with Selena's announcement please stop relating them to each other - both have their own happy life now!"

After a long back and forth over social media this year, Hailey recently told-all about her current relationship with Selena on the Call Her Daddy podcast.

She said: "It's all respect, it's all love.

"There's no drama, personally. If everybody on our side knows what happened and we're good and we could walk away from it with clarity and respect, then that's fine."