Gwen Stefani revealed that when it comes to her marriage with Blake Shelton — whom she met while coaching “The Voice” in 2015—the key to a happy relationship lies in a “third party.”

Shelton and Stefani first met as coaches on The Voice, the long-running singing competition that currently has Kelsea Ballerini, Adam Levine, John Legend, and Michael Bublé on its coaching roster. Stefani was married to Gavin Rossdale at the time; Shelton was married to Miranda Lambert. Both subsequently filed for divorce.