Jennifer Aniston's friendship with Courteney Cox has reportedly become "strained" since she started dating Justin Theroux.

The pair have been inseparable since meeting at the Friends audition in 1994, but Courteney apparently feels Jennifer has "forgotten" about her since moving in with Justin.

"Jennifer's priorities have obviously changed since meeting Justin," a source said.

Courteney, 47, supported Jennifer through her 2005 divorce from Brad Pitt, and often invited her to holiday with husband David Arquette and their seven-year-old daughter Coco. But the Scream actress is now alone having separated from David in 2010, and is said to be feeling neglected by her loved-up best friend.

"Courteney must feel that Jen has completely forgotten what it's like to be the single girl and that will hurt given how supportive she and David were to Jen over the years," the source added.