Robert Pattinson spends the weekend partying without Kristen Stewart

Robert Pattinson partied with Natalie Portman at hubby Benjamin Millepied's ballet Moving Parts at Walt Disney Concert Hall in L.A. on Saturday.

The actor was "relaxed and happy" as he drank beer and puffed on an electronic cigarette, reports OK.

"He was there the whole night," a source said. "He came at 5:30 and didn't leave until the end of the after party."

Rob was also spotted Jimmy Kimmel's post-Emmys party on Sunday night.

It's been quite the summer for Rob after his girlfriend of 4 year, Kristen Stewart, was caught cheating with Snow White and the Huntsman director, Rupert Sanders.