Robert Pattinson’s Ultimatum to Kristen Stewart: “It’s Me or Michael!”

Say what you will about Robert Pattinson—the guy won’t stand for two-timing.

OK! Magazine reports that the Twilight heartthrob has delivered an ultimatum to his co-star and rumored love interest Kristen Stewart—either break things off with her boyfriend, Michael Angarano, or it’s over between them.

Though Angarano has been out of the picture in recent weeks, he and Stewart have apparently yet to officially end things—and R-Pattz thinks it’s high time they did.

“Robert is completely frustrated. If Kristen isn’t interested in a serious relationship, she needs to tell him so he can move on,” says a source.

Pattinson, currently in New York to film the upcoming romance Remember Me, is reportedly giving Stewart a couple of months to sort out her situation with Angarano, but he’s not willing to wait forever. He expects K-Stew to make her decision before the two return to Vancouver in the fall to begin filming Eclipse, the third installment in the hugely successful Twilight movie franchise.

“He’s asked her to choose between him and Michael this summer,” the mag’s source notes. “Robert’s not willing to be strung along.”

Sounds like Kristen has a lot of thinking to do.

Readers, have your say in the comments section: What do you think Kristen Stewart should do?