Kim and rapper Kanye West exchanged vows in Florence, Italy on 24 May, following a week of pre-wedding celebrations in Paris, France.
Rob had been seen with his family in France but abruptly jetted back to LA the day of Kim's wedding, while the rest of the Kardashian-Jenner clan travelled to Italy for the nuptials.
During an interview on Good Morning America today, his siblings Kendall and Kylie declined to explain his mysterious absence, but did insist: "He's doing really well."
As none of the Kardashian-Jenner family have revealed why Rob left the wedding, speculation has run rife, with sources claiming everything from a family row to Rob being unhappy over his recent weight gain and not wanting to be photographed.
While Kendall, 18, and Kylie, 16, wouldn't elaborate on Rob's mindset, they did gush about Kim and Kanye's fairytale wedding, which took place at the 16th century Fort Belvedere.
"Everything was amazing," said Kendall. "To see two people so happy, I think that was probably my favourite part."
Kylie added: "The whole wedding was just filled with so much love. It was just really amazing to watch that."
The siblings also revealed that Kim and Kanye chose their outfits for the big day. (Are we surprised?!)
Following the Italian nuptials, Kim - who is now called Kim Kardashian West - jetted to Ireland with Kanye for their honeymoon. They then travelled on to Prague for a friend's wedding before Kim returned to the US.
Their baby daughter North, eleven months, was being looked after in LA by Kim's mum Kris Jenner.
Meanwhile, brother Rob has been supporting sisters Kendall and Kylie today, urging his five million Twitter followers to buy their debut novel Rebels: City of Indra.
Reveal is now on Google Plus! Join us here for the latest pictures, fashion and celebrity news!
Got an iPad or iPhone? Reveal Mag is specially designed to fit!
What did Kim and Kanye do on their honeymoon? Check out the fun photos!
Copyright: Alison Jackson