People.com reports the couple flew to New York to celebrate Theroux’s 41st birthday on August 10, and the “Wanderlust” actor took the opportunity to pop the question.
"He's been dying to do it," said a Theroux pal. "His friends knew it was coming."
Aniston, 43, then gave him "an extraordinary gift" by accepting. Afterwards, the two called their friends and family to share the news.
"Everyone is really excited for them," added another source. "It's amazing to see how happy Justin makes Jen, and everyone was always hoping that he would propose."
Actor-screenwriter Justin Theroux had been “dying” to propose to his love Jennifer Aniston.