Start planning the bachelor party! The Hangover Part III actor Justin Bartha is engaged to Lia Smith, multiple sources confirm to Us Weekly.

The 34-year-old star proposed to the fitness trainer in early May while on vacation at Post Ranch Inn in Big Sur, Calif., an insider tells Us.

“They’re the cutest couple. She was completely surprised by the whole thing,” the source adds. “The trip to Big Sur, the engagement, the ring, everything. So cute.”

The insider tells Us that The New Normal star popped the question with an engagement ring that is “just unbelievable.” “They are an amazing couple,” the source adds, “and so gorgeous together.”

Bartha and Smith took their relationship public in January 2013 when they were spotted relaxing on a beach in Maui, Hawaii together on New Year’s Day. The two met during a Pilates session at Equinox in L.A., where Smith is an instructor.

This will be Bartha’s first marriage. He previously dated Ashley Olsen for two years before calling it quits in March 2011.