The actor began dating the `Horrible Bosses` actress earlier this year and while there have been reports the smitten couple are set to tie the knot, his pal Craig Wedren claims it won`t happen.
Craig insists Justin - who was with girlfriend Heidi Bivens for 14 years before reportedly leaving her for Jennifer - is not the marrying kind as he doesn-t like to be tied down.
Craig - who composed the music for the film `Wanderlust`, where Justin and Jennifer first met - said: "Justinwillnevermarry her. He`s not the marrying type - as you can see from the 14-year relationship he was in that didn`t end in marriage.
"He is not the kind of guy to be owned."
He says Justin, 40, and 42-year-old Jennifer are complete opposites of each other and can`t see them lasting.
He told InTouch Weekly magazine: "Jen is the complete opposite of Justin. She`s all about Malibu and shopping and trying to stay young while Justin is about being an artist.
"The last place Jen would want to go in New York would be a dive bar."
The composer also claims Justin was "very taken" when he met and fell in love with the former `Friends` star.
He added: "He totally lied to Heidi and broke her heart."