His onscreen alter ego got into trouble when he headed out of town leaving his significant other behind in The Hangover.

But Justin Bartha showed that life doesn't always imitate art as he took his new fiancee Lia Smith along for a flight out of Los Angeles, on Tuesday.

And it was clear that the 34-year-old had successfully steered clear of his scripted cinematic foibles as he and his love brandished irrepressible smiles en route to their departure gate at the LAX airport.

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Heading out: Justin Bartha and new fiancee Lia Smith were all-smiles as they strolled to departing flight out of LAX airport, on Tuesday

Justin opted for comfort as he donned a matching army green snap back cap and trousers for the day of travel.

Completing his casual getup were white trainers, a grey graphic T-shirt, and a black nylon jacket.

The actor maintained a firm grip on his lovely lady's hand as he guided her into the airport terminal.

Cool duo: The pair of fitness buffs donned nearly matching sunglasses for their day of travel

Lia for her part was a bit more stylish than her movie star beau.

The fitness trainer wore knee high leather boots over black skinny jeans.

Adorning her toned torso was a slinky white tank top as she tied her jumper around her slim waist.

Newly out: Justin made the engagement public last Friday

The two have kept their engagement under wraps since early May, but multiple sources confirmed the engagement with Us Weekly , as announced Friday.

The actor reportedly proposed to the Equinox trainer while on vacation at Post Ranch Inn in Big Sur, California, at the start of May.

A source told Us that The New Normal star popped the question with an 'unbelievable' ring.

Big year: Justin pictured at the premiere for Hangover Part 3 in Westwood, California, on Monday

The pair made their relationship public in January when they were spotted on a beach in Maui, Hawaii, on New Year's Day.

Their mutual love of fitness is what brought them together, as they met during a Pilates class at Equinox in Los Angeles, where Lia is an instructor.

The actor is gearing up for a very exciting second leg of 2013, as the release of the third and final installment of The Hangover will hit theatres Friday, May 24 in the U.S.