updated 11/08/2010 AT 10:00 AM ET
•originally published 11/08/2010 AT 11:30 AM ET
The superstar singer, 29, has quietly been seeing Matthew D. Rutler, a set assistant from her upcoming movie Burlesque – whom she tried to hide from the cameras Friday when they enjoyed a double date at SoHo House in Los Angeles with friends Nicole Richie and Joel Madden.
A friend tells PEOPLE that the relationship with Rutler started as a friendship, then turned into something more.
“It’s not serious yet, but it’s something she is exploring and finding comfort in,” the friend says. “It’s new and she s taking it day by day. She and Jordan were having problems for a long time. What kept them together is their love for their son. She met [Matthew] on set and, during a difficult time, leaned on as a friend. After she and Jordan separated, the friendship turned romantic.”
The friend adds that Aguilera’s son Max, who’ll be 3 in January, is still the singer’s No. 1 priority. “Being a great mom to Max is the most important thing in her life,” says the friend.
Aguilera makes her acting debut with Cher in Burlesque, a cabaret drama that opens Nov. 24.