They ramp up their relationship with a theater visit and a night of clubbing

Credit: Denise Truscello/WireImage; Nick Sadler/Startraks

Audrina Patridge and singer Ryan Cabrera have gone public – on both coasts now – with their courtship.

On Wednesday night in Los Angeles, The Hills star, 24, and Cabrera, 27, attended R&B singer Ray-J’s birthday party at Wonderland nightclub, where they made little effort to hide their affection for each other. “They never left each other’s side,” an eyewitness tells PEOPLE. “They were flirting all night and sipping from each other’s drinks.”

And just a few days earlier, on Sunday night, Patridge and Cabrera (whose exes include Riley Keough and Ashlee Simpson-Wentz) attended the Broadway musical Rock of Ages, starring American Idol alumnus Constantine Maroulis, at Manhattan’s Brooks Atkinson Theater.
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Occupying a pair of seats on the aisle, six rows from the stage, the lovebirds “arrived together, and no one seemed to recognize them, they flew right under the radar,” a fellow theater-goer tells PEOPLE. “They had drinks at their seat. They totally looked like a couple. It was really cute. They were holding hands and her hand was on his leg. They were very smiley with each other, and joking around.”

Despite being in a very public setting, the theater-goer says, “They wouldn t pose for photos though which was weird because they totally came and left together.” And the pair reportedly didn’t end the night there: They were overheard “talking about going out after the play that night.”

With additional reporting by MARISA LAUDADIO and JENNIFER GARCIA