The 26-year-old British heartthrob - who forgave and reconciled with the 22-year-old 'On The Road' actress following her "momentary indiscretion" with her 'Snow White and the Huntsman' director Rupert Sanders last summer - is said to have ended their four-year relationship over the weekend after a difficult few weeks together.
A source told The Sun newspaper: "She flew to LA and was supposed to be Rob's date for the Golden Globes, but he told her he wants to cool it off.
"He loves her but would rather go back to being good friends so they can rebuild their trust and focus on work after 'Twilight'.
"Kristen's upset but understands. She shouldn't have pushed him to reconcile after her infidelity. She's hoping he'll come round and time will be a great healer.
"He was getting so much pressure to ditch her. His friends told him to focus on his career and said she was wrecking his chances."
The insider also revealed that Kristen is now planning to move to New York and Robert will continue to live in Los Angeles.
The friend said: "She feels people leave her alone there and she has a bit more peace."
News of the couple's split comes just days after they were spotted at a Golden Globes afterparty together.
The 'Twilight Saga' couple put on a united front at award hosts Tina Fey and Amy Poehler's private celebration held at Soho House in West Hollywood after the prestigious ceremony on Sunday night.
Robert looked dapper as he walked the red carpet, where he jokingly presented Tina with a rose. The 'Cosmopolis' heartthrob then headed off to the party solo.
Meanwhile, Kristen avoided the Golden Globes altogether and arrived at the VIP after-party in altogether more casual attire at 1am. She teamed jeans and a baggy sweatshirt with trainers and a backwards cap, hiding her eyes behind shades as she snuck into the star-studded event.