Dun, 30, popped the question to the 25-year-old actress and singer, who currently stars in the Netflix series Insatiable. The couple had been dating on and off since 2013.
"I found a tree house in the woods in New Zealand and proposed to my girl," Dunn captioned several photos of the joyous occasion, including a shot of the engagement ring. "She my dude for life. I love you Debby."