Keith Urban is revealing the secret to his successful relationship. Urban and actress Nicole Kidman have been married for 17 years, but during an interview with Fox News Digital ahead of the ACM Awards, the singer shared it is not always easy managing his career with his personal life. The rule that works for them? "It’s always family first." "It's balanced, so it means it goes out of balance sometimes, and we just put it back in balance," Urban said. "It's never perfectly in balance, but we get it back on track." What are your personal keys to a successful relationship?