Having just returned from overseas trips to promote Breaking Dawn Part 2 -- Pattinson was in Australia, while Stewart was in Japan -- the couple hit the town for their first big night out together since landing back in Los Angeles.
The normally PDA-shy pair arrived early at the venue and promptly huddled together in a corner booth. They were with friends, but witnesses said they seemed to have eyes only for each other.
"Rob and Kristen were inseparable," a fellow Prince fan told Us Weekly. "They were so lost in each other, it was ridiculous. They looked just like they do in the movies...completely in love.
"They were talking very closely all night, laughing, kissing, holding hands, arms around each other," the onlooker continued, adding that they seemed to pay little attention to any of their friends. "Everyone just let them be."
At one point while the band was warming up, Pattinson -- casually dressed in low-slung jeans, a T-shirt, a black jacket, and a baseball cap -- draped a protective arm around his on-again love.
"They looked very natural together. Watching them, you would never know the scandal that erupted," the witness said, referring to Stewart's recent tryst with her Snow White and the Huntsman director, Rupert Sanders. "I didn't see them argue once."
Once the music got going, the Cosmopolis actor was "the life of the party," grinning and dancing up a storm while downing Grey Goose vodka drinks and beer. Stewart was more reserved, the source told Us, but she loosened up as the night went on.
"She seemed happy," the onlooker said, adding that their PDA "didn't look forced."