Kristen starred with Riley in The Runaways

Kristen Stewart is reportedly ‘devastated’ by the news that Robert Pattinson is dating her former co-star and friend Riley Keough.

Model and actress Riley – the granddaughter of Elvis Presley – was spotted driving around LA with Rob, 27, at the weekend and also spent much of last week with him.

And pals say things are quickly hotting up between the new couple.

They’re inseparable,’ a source says.

Rob and Riley have been spending much more time together since meeting through their Dior modelling connection and Riley has stayed over at Rob’s Los Feliz apartment.

They have a lot in common – they both love LA, London, rock music and table tennis.

Rob loves the fact that Riley is Elvis’s granddaughter – that’s true rock’n’roll royalty in his eyes.’

Rob first met Riley, 24, when she co-starred with Kristen in 2010 film The Runaways and K-Stew, 23, is said to be ‘livid’ that they’re now dating.

Kristen feels that she acted as mentor to Riley on her first film The Runaways, introduced her to Rob and encouraged her to make a career of acting,’ the source tells Mail Online.

Rob has been made aware through friends that she is devastated.’

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Anna Francis