We finally have an answer to Bezos wedding question that had everyone scratching their heads: Why was Sydney Sweeney there?

The 27-year-old was spotted among the many celebrities and high-profile guests of Jeff Bezos, 61 and his new wife Lauren Sanchez, 51, at their reported $US50 million (approx. $76 million) wedding in Venice, despite having no discernible link to the couple.

Now, a source has revealed why the rising star was invited to the wedding of the century.

The source explained to Page Six that Sweeney's invite has to do with her recent casting in the film adaptation of the video game Split Fiction.

The project – which will be directed by Wicked and Crazy Rich Asians director Jon M. Chu and written by Rhett Reese and Paul Wernick of Deadpool & Wolverine – was picked up by Amazon MGM Studios in June.

This seems to have caused the Amazon CEO to add the Euphoria actress to his wedding.

Page Six's source says that Sweeney simply "came to pay respect to the 'boss,' just like in the old days of Hollywood."

They added that the Anyone But You actress is "not friends with either one of them".

Sweeney isn't the only guest at the billionaire's wedding that had everyone confused.

The Kardashian-Jenner family stole the show during the three-day extravaganza, with their refined outfits for each occasion.

Kardashian-Jenner matriarch Kris Jenner, who attended the wedding with daughters Kim and Khloé Kardashian and Kendall and Kylie Jenner, has been close friends with Sánchez for a while.

Last year, Kris shared a post with her millions of followers from her catch up with the journalist and ex of Hollywood talent executive Patrick Whitesell, 60.

"Rainy day lunch with my girl @laurenwsanchez 🥰," she wrote at the time.

Kim initially grew close to Sánchez talking about fashion and Kim previously praised her for being "such a girl's girl" to Vogue.

"Lauren and I are always sending DMs building each other up," she said.

Kris and Khloé were also in attendance when Sánchez went to space during the Blue Origin Space launch in April, watching the history-making moment from the ground.

Sánchez was also on board the flight with pop star Katy Perry, so it's believed she knows actor Bloom through Perry, who he is rumoured to have just split with.

The wedding was also attended by Oprah, Jessica Alba, Leonardo DiCaprio, Ivanka Trump and NFL sporting great Tom Brady.

Singers Usher, Jewel and Ellie Goulding and even Australian actress Deborra-lee Furness scored an invite to the lavish nuptials.

They were also joined by non-celebrities such as tech billionaire Bill Gates and his girlfriend Paula Hurd, media magnate Lachlan Murdoch and model wife Sarah Murdoch, Ivanka Trump and her husband Jared Kushner, and others from the "billionaires club".

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