Aniston, 43, who is set to marry Theroux, recently returned to LA during a break from filming "We're the Millers" in North Carolina with Jason Sudeikis, reported People magazine.
"Jennifer looked adorable! She looked so pulled together and very chic. She was dressed casually, but in heels.
"They were very calm and carrying on a regular dinner conversation. Jennifer had a big smile on her face. She and Justin both looked very happy," a source said.
It was the first time Aniston and Theroux have been seen out together since their August 12 engagement.
