Gwen Stefani would never have imagined she'd fall in love with Blake Shelton in her "wildest, craziest dreams".

Gwen Stefani

Gwen Stefani

The 46-year-old singer was stunned when she returned to work on 'The Voice' in the wake of the not-yet-public breakdown of her marriage to Gavin Rossdale - the father of her sons Kingston, nine, Zuma, seven, and Apollo, 22 months - and discovered her fellow coach had separated from his spouse Miranda Lambert, and they quickly forged a close friendship.

She said: "[Blake] had been going through literally the exact same thing in literally the exact same time frame...

"Never in my wildest, craziest dreams would I ever have seen this coming."

Songwriter Justin Tranter, who was working with Gwen on her solo album 'This Is What the Truth Feels Like' at the time, noticed a change in his collaborator instantly.

He recalled to the New York Times newspaper: "We had anger, we had sadness, we had flirtation, we had sexy, and now we're madly in love."

Gwen was approached to work on 'The Voice' shortly after the birth of Apollo and, having embarked on tours soon after her other sons were born, it was just the change she needed.

She said: "I needed so badly to do something different, and I needed so badly to be in a different role, a giving role."