Jennifer Aniston joined by her boyfriend Vince Vaughn attend the screening of The Break-Up in Germany (06/12/06).

Jennifer Aniston is blaming boyfriend Vince Vaughn for her failure to quit smoking.

The actress is said to be desperate to give up, but her partner's love of cigarettes is making it a difficult task.

A source told Britain's Daily Express newspaper: "Jen has been in trouble with her doctor because she went to him for help in giving up and she hasn't.

"Every time she tries, there would be Vince puffing away. He's not helping in the least and when she tells him off about it, he laughs."

Despite struggling to quit, Jennifer is said to be determined to give up - when the couple start a family.

The source added: "She's convinced that the day she falls pregnant will be the day she and Vince stop. She just needs that extra incentive."