"I would be shocked if they're not married before 2012, for sure," Harrison said.
Harrison credits the couple -- who got engaged on the sixth season of The Bachelorette last summer and are now "doing great" -- for their attempt to settle into a normal life in a San Diego apartment away from the limelight in Los Angeles.
"What I love is that they're living their lives," Harrison told People. "I try to tell them, 'Don't let The Bachelor change who you are. Just let it enhance what you do...' I think those successful couples have been able to do that."