The couple, who were first spotted together last summer, hit the Pussycat Dolls Lounge in celebration of Long’s brother Christain’s 26th birthday.
“They were very affectionate,” an onlooker tells PEOPLE of the celeb couple.
After catching the 11:30 p.m. show and toasting the birthday boy with champagne, Barrymore, 32, and Long, 29, headed to Noir Bar– where they sat at a VIP table and downed Grey Goose vodka and soda.
“They looked adorable,” a source tells PEOPLE.
Also at Noir was singerChris Daughtry and his band.
– David Caplan, Jennifer Garcia and Mark Gray