The singer/actor, who was born in South Africa but was raised in Australia, recently proposed to Jillian in New York City after six years of dating, and she said yes.
However, a representative for the couple reveals Dean had to rethink how to pop the question after his initial plans to get down on bended knee while on their annual end-of-year trip Down Under didn't work out as Jillian could no longer make the vacation.
"He had to quickly change the plans and decided he wanted to do it in a photo booth," the spokesperson tells People.com. "He knew he could get the pictures but still have it be a private moment.
"So after attending a Broadway play, he took her to a photo booth and got down on one knee while the camera was flashing so they could capture the moment forever with Jillian's dream ring, a flawless two carat diamond."
The couple met on the set of 2011 sports drama Never Back Down 2: The Beatdown, and Dean previously admitted he is thankful for that film role.
In 2011, he told the Daily Telegraph, "I'm really, really happy now... We've been together for a year. I'm so glad I did that movie, for sure."