Lia and Justin in Hawaii New Years Day
Pacific Coast News
01/07/2013 at 07:00 PM EST
Justin Bartha's "mystery woman" is in fact his girlfriend, trainer Lia Smith, a source reveals to PEOPLE.
The pair recently enjoyed a cozy trip to Smith's native Hawaii and were snapped basking in the sun on Maui on New Year's Day, which got people buzzing about her identity.
"They were very cute with each other," says an eyewitness. "They had their arms around each other and were kissing."
The couple also spent time with Smith's parents on Oahu. Bartha, who currently stars on The New Normal
, was previously linked to Scarlett Johansson
and dated Ashley Olsen
for two years before breaking up