Kendra Wilkinson shared a throwback picture of her ex-boyfriend Hugh Hefner on Instagram on Sunday.

The picture, which featured Wilkinson cuddling up to the Playboy founder while holding a bottle of champagne, was captioned, "Happy birthday Hef!! Thank you for EVERYTHING. People might not understand you but that's because they've never had the chance to know you like I do. I'll celebrate you forever!!!"

The "Kendra on Top" star dated Hefner from 2004 to 2008 and was featured on the E! Show "The Girls Next Door" along with Holly Madison and Bridget Marquardt.