07/01/2011 at 02:15 PM EDT
They may not have made their red carpet debut together at Thursday's Horrible Bosses premiere
in Los Angeles, but Jennifer Aniston
Justin Theroux was there to keep her company.
After meeting up inside the premiere, the couple hit Chateau Marmont just past 10 p.m. with a large group of pals, including Aniston's BFF Courteney Cox
and Chelsea Handler.
Aniston, 42 – still clad in her Balenciaga dress from the film's premiere – wore Theroux's jacket walking in. Theroux, 39, played the part of dapper boyfriend in a black suit, white shirt – and a clean-shaven face!
"They were super cute," says an onlooker. "He had his arm around her and kissed her on her cheek. They were whispering in each other's ears."
Theroux seemed to fit in with Aniston's close-knit crew just perfectly. "Everyone seemed to be getting along and in a celebratory mood," adds the source.