(LOS ANGELES) -- Kristen Stewart has reason to frown these days. She and her boyfriend, Twilight co-star Robert Pattinson, have broken up.
This is according to People magazine, which cites an unnamed source who also says it would not be surprising if Stewart and Pattinson eventually reconciled.
In a separate People report, an insider is quoted as saying, "Kristen has been in a terrible mood, and it was obvious that things were not great with Rob."
The magazine notes that Stewart did not attend a 27th-birthday celebration for Pattinson at his home on May 13. A source says, "For the past few days, they have not spent any time together."
Us Weekly adds that the two had been "fighting a lot" prior to Pattinson's birthday.
Stewart and Pattinson have dated for more than three years, aside from a brief split last summer, when Stewart revealed that she'd had an affair with her married Snow White and the Huntsman director, Rupert Sanders.
Copyright 2013 ABC News Radio