Jennifer Aniston has started to reveal her high maintenance behaviour to boyfriend Justin Theroux, it is reported.

The 42-year-old actress and the hunky actor/director, 40, have been dating for nearly a year now, but Jennifer's obsessive actions are starting to affect their relationship.

In Touch Weekly claims that the former Friends star has become more concerned about her weight after gaining 10lbs when she gave up smoking in a bid to have a baby.

But now she "complains nonstop about how fat she is" which is wearing on Justin, the publication reports.

"Justin really can't believe how vain Jennifer is," the insider said. "He will want to go to a restaurant and Jen will say that the food's too fattening or that she can't stay up late because she's getting up at 6am to go to a workout."

The source also alleges that Jennifer is controlling their love life by only wanting to be intimate during her more fertile days, in her bid to become a mother.

Jennifer's command over their social life is also said to be an issue for the free-spirited actor.

The Horrible Bosses star apparently made plans for them to visit with her friend Courteney Cox on Christmas Eve but Justin "flat out said no."

"He sort of rebelled and said he wasn't sure about going. He's starting to feel like Jen is scheduling all of his time up so that he won't be able to see friends."

Although her rep says the relationship is fine, Jennifer also thinks that it is "unhealthy" that Justin still talks to his ex-girlfriend Heidi Bivens who he was with for 13 years.

"They may end up spending time apart," the pal added if Jen does not loosen the ties on the relationship.