Robert Pattinson and Kristen Stewart have officially broken up...but Kristen's still jealous and making trouble.

Kristen Stewart is not happy about Riley Keough, her former friend, hooking up with

Robert Pattinson, her former boy toy-and she called Keough to let her know.

Riley Keyough is also Elvis Presley's granddaughter, and Kristen isn't happy about her seeing Pattinson. Reportedly, she let her know in no uncertain terms.

 "[Kristen] called Riley. She likes and respect her, but she just doesn't feel like it is ever right to go after a good friend's ex who is suddenly on the market," an insider allegedly said to press.

However, Kristen was apparently calm and mature...which is a new turn of events and newsworthy in itself. The "Twilight" actress was calm in her alleged conversation with "Runaways" co-star and still let her know her feelings-namely, that she is NOT happy about the sitch.

Riley, on the other hand, is torn between two friendships. She feels bad that Kristen is so upset...but she doesn't want to choose between Stewart and Pattinson.