The former Friends star grew close to Theroux during filming of the romantic comedy in 2010, and they began dating last summer (11).
Rumours suggest a romance sparked up on set, while Theroux was still dating stylist Heidi Bivens, but Aniston is adamant "nothing happened" while they were working.
She tells Good Morning America, "Nothing happened on that movie... That was just a rumour, the easy rumour.
"We were just friends. I’ve known Justin for a long time."
Could it be that after all this time of searching Jennifer Aniston has finally found a love that will stick? For years America has waited with baited breath for Jennifer to find a man to fill that void that Brad Pitt left behind. Men have come and gone and then come back again, but will Justin Theroux be the one to cancel out all that unlucky love karma?
Aniston has already started calling Theroux her boyfriend - something she hasn't done since her on-again, off-again relationship with John Mayer. Theroux has been seen in such movies as Zoolander and will be in the upcoming movie with Aniston, Wanderlust, and considering Aniston has been known to fall for several of her co-stars (including Gerald Butler from Bounty Hunter and Jason Bateman from The Switch), this romance seems all the more plausible.
It's great that the beautiful actress finally seems to be getting her love life back on track, but one could point out that they may be moving too fast even in the celebrity world. An insider announced "He's living at her place in L.A.!" This is a huge step for a couple that just went public with their relationship earlier this month. Let's also not forget that it hasn't been that long since Theroux's split with his 14 year love interest with costume designer, Heidi Bivens. The couple lived together for 6 years and she only moved out last weekend. Is Theroux experiencing empty nest syndrome or is Aniston really the one for him? Only time will tell...
The actor/director worked with the former Friends star on new movie Wanderlust and they sparked speculation of a romance when they were spotted dining together in Los Angeles. They also appeared at an afterparty for this month's (Jun11) MTV Movie Awards, smiling and posing for pictures together.
It has now emerged that Tropic Thunder writer Theroux recently ended his relationship with his long term girlfriend Heidi Bivens and she has now moved out of the home they shared.
A representative for Bivens has confirmed the split to New York Post gossip column Page Six: "Heidi and Justin have been together for 14 years. They met when she was 20 years old and he 24, and yes, she just moved out of their home last weekend. She has no comment."
A source adds, "Things were already over between him and Heidi before he got close to Jen."