We can only speculate on what kind of "Hangover"-fueled tomfoolery his bachelor party might entail.
Bartha, 34, proposed at the Post Ranch Inn with an "unbelievable" engagement ring, the mag's sources said.
A rep for Bartha did not immediately respond to the Ministry's requests for comment.
Bartha and Smith met during a Pilates session at an L.A. gym where Smith works as an instructor. They debuted their romance this January while vacationing in Maui.
This would be the actor's first marriage. He was previously linked to actress-turned-designer
The third installment of the film's franchise hits theaters Thursday, with Bartha's costars
Bartha can next soon be seen playing Dead Boys singer Stiv Bators in "CBGB."
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