Justin Bartha is best known for his disappearance the night before his wedding in The Hangover. Let's hope for his sake that life doesn't imitate art, as the actor will be saying "I do" in real life.

The 34 year-old star recently popped the question to his personal trainer girlfriend Lia Smith earlier this month while vacationing at Big Sur. "They're the cutest couple. She was completely surprised by the whole thing. The trip to Big Sur, the engagement, the ring, everything. So cute," a source close to the couple said.

Bartha - who previously dated Ashley Olsen for two years before splitting up in March 2011 - met Smith at an Equinox gym in Los Angeles, where she works as an instructor. The pair went public with their romance back in January, when they were spotted spending New Year's Day together in Hawaii.

No word yet as to when they plan to tie the knot.