updated 10/22/2010 AT 1:00 PM ET
•originally published 10/22/2010 AT 2:25 PM ET
Simpson was on a date with boyfriend Eric Johnson, while Lachey was with longtime girlfriend Vanessa Minnillo when the foursome all showed up for dinner at Hollywood hotspot The Red O.
Simpson, 30, and Lachey, 36, ended their marriage five years ago, but the former Newlyweds stars’ encounter was surprisingly drama-free.
“They didn’t interact,” says a source. “They didn’t even come to face-to-face with each other.”