08/13/2012 at 07:20 AM EDT
is getting married to boyfriend Justin Theroux!
"Justin Theroux had an amazing birthday on Friday, receiving an extraordinary gift when his girlfriend, Jennifer Aniston, accepted his proposal of marriage," his rep tells PEOPLE exclusively.
Aniston, 43, and Theroux, 41, an actor-screenwriter, have been dating
for more than a year.
The couple – who both starred in Wanderlust
– were first spotted together in May 2011.
"They are great friends," a source told PEOPLE at the time
During an interview on Good Morning America
the next month, when asked about her personal life
, Aniston couldn't hide her emotions.
"Yes, I'm very happy. I'm extremely lucky, and I'm extremely happy," she said.