Kristen Stewart is said to be "heartbroken" after breaking up with Robert Pattinson again.

The 23-year-old actress is "so sad" after the Twilight co-stars reportedly called it quits - for now - after more than three years of dating, reported People.

"She hasn't left her house for days, but [has] surrounded herself with friends 24/7," a source told the magazine.

The couple, who played lovers Bella Swan and Edward Cullen in the Twilight films, apparently started to grow distant after Rob returned from New York to Los Angeles on May 8.

"They again went from spending every second together, to spending more time apart at their separate houses," the source said. "Kristen has been in a terrible mood, and it was obvious that things were not great with Rob."

The pair split briefly last year after Kristen had an affair with married Snow White And The Huntsman director Rupert Sanders, but later rekindled their romance. They were seen putting on a rare show of public affection at the Coachella music festival, celebrating the actress's 23rd birthday in April and spending time together in New York.

But Kristen was apparently absent from Rob's 27th birthday on May 13.

"It was very strange that they didn't celebrate Rob's birthday together. He had friends over at his house, but Kristen was not part of the celebration. For the past few days, they have not spent any time together," the source continued.

Another insider told E! News that the split is only temporary and that they are working out their priorities. "They are going to stay living at Kristen's house because of the dogs. It's not fully over or he would have moved out. They will be back together in no time," said the source.