Neil Diamond's wife is his "best friend"

Katie told People magazine: "We're best friends, and we really support each other. We lift each other up, and through thick and thin, through sickness and health, we really live it. And I think that that's the secret.

"And it's our 14th wedding anniversary coming up in April."

But the couple don't feel the need to mark their wedding anniversary in a particular way because they try to "celebrate" their love on a daily basis.

Katie said: "I mean, every day we try to make it special and celebrate every day."

Neil's music is in the spotlight thanks to upcoming new movie Song Sung Blue, which is about real-life couple Mike and Claire Sardina - who are played by Hugh Jackman and Kate Hudson - who founded Neil Diamond tribute act Lightning + Thunder.

And Katie was very emotional when she watched the movie and heard Kate singing I've Been This Way Before.

She admitted: "When she sang it, I was sobbing. It brought me to tears. It is such a beautiful song."

Neil - who has four children from his previous two marriages - previously told how his romantic feelings towards Katie developed over time when they began working together.

He told the Daily Telegraph newspaper: "We kind of fell in love, slowly. She wove her way into my heart, and I think she's a great person. I realised that I was in love with her."

Katie felt reluctant to make their relationship more than professional.

She told Parade magazine: "Part of me said, 'Don't get involved; he's a client.'

"There are a lot of complications for a lot of reasons. But our chemistry grew into something that couldn't be denied."

The Sweet Caroline singer feels like the "luckiest man on the face of the earth" to be married to Katie.

He also told Parade: "I don't want to end this whole fabulous journey alone.

"I want someone by my side who I love and who loves me. I've finally found somebody who's up to the task of being my wife, because I'm very ... high-maintenance.

"I think I'm probably the luckiest man on the face of the earth."