updated 01/21/2010 AT 1:00 PM ET
•originally published 01/21/2010 AT 1:40 PM ET
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.