Cover Story: Rob Tells Kristen to Choose

On June 1, the morning after their smoldering, almost-but-not-quite kiss at the MTV Movie Awards, Twilight twosome Robert Pattinson and Kristen Stewart stayed in a 1920s bungalow at The Charlie, a West Hollywood hotel named for onetime resident Charlie Chaplin.

Fittingly, they bunked in a cottage called the Valentino – as in Rudolph, the silent-screen romantic idol – and it made for an idyllic nest, with its two bedrooms, two baths, full kitchen and even a quaint window seat.

"They were very sweet together," an insider tells OK! of Kristen and Robert. "They were lovely."

But before the vampire saga's global fan base gets all dewy-eyed, there's a bit of a glitch: Kristen, by all accounts, is still involved with her longtime boyfriend, Michael Angarano. The results? A love triangle of Brangelinian proportions.

R-PATTS & KRISTEN:

Clearly, something's got to give – and insiders tell OK! that "Edward" has handed his "Bella" an ultimatum: Make up your mind, or drive a stake through it; we're done.

"Robert is completely frustrated. If Kristen isn't interested in a serious relationship, she needs to tell him so he can move on," says one source, adding that R-Patts, 23, is giving 19-year-old Kristen a couple months to sort things out while he's in NYC filming Remember Me, an indie flick about star-crossed lovers (production begins June 15).

The actor wants a resolution by the time he and Kristen reunite in Vancouver this fall to shoot Eclipse.

"He's asked her to choose between him and Michael this summer," says the source. "Robert's not willing to be strung along."

For more, pick up the new issue of OK! – on sale everywhere Thursday – to find out the latest on the onscreen lovers!