"We are grateful for the years we've spent together and believe wholeheartedly that we did our best," the couple tells PEOPLE in a statement

After four years of marriage, The Real Housewives of Beverly Hills star Yolanda Foster and her husband, songwriter and record producer David Foster, have decided to end their marriage.

“Sadly we have decided to go our separate ways,” the couple tells PEOPLE in an exclusive statement. “We’ve shared nine beautiful and joyous years together. During that time we experienced love, friendship and the inevitable challenges that come with managing a marriage, careers, blended families and health issues.”

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The reality star, 51, has three children from her first marriage to Mohamed Hadid: Gigi 20, Bella, 19, and Anwar, 16.

Foster, a 16-time Grammy award winner, has been married four times and has five daughters.

At their fairy tale wedding on Nov. 11, 2011, David, 66, told Yolanda: “Tonight, I’m the luckiest man on the planet.”

And when the couple recently put her their Malibu mansion on the market, Yolanda wrote on Instagram: “Beautiful ending to a beautiful chapter of our life,” alongside a romantic picture of David with her by their pool at sunset.