Robert Pattinson has had enough of being rejected by co-star Kristen Stewart and has demanded that the actress choose between him or her longtime love Michael Angarano. "Robert is completely frustrated," a friend of his told OK Magazine! "If Kristen isn't interested in a serious relationship, she needs to tell him so he can move on." The source said that Robert Pattinson is giving Kristen Stewart a few months to sort out her feelings. Pattinson wants the issue resolved by the time the two re-unite in Vancouver for the filming of Eclipse, the third installment of the Twilight franchise. "He's...