Nicole Kidman and Keith Urban had reason to celebrate on Friday as they marked their 15th wedding anniversary.MORE: Keith Urban shares moving rare photo of daughters and wife Nicole KidmanThe country singer took to Instagram to share a sweet selfie of the couple – which had been taken over the festive period – showing them both embracing in front of a Christmas tree.In the photo, the pair were wearing matching Christmas pyjamas emblazoned with candy cane and ginger man cartoon prints. VIDEO: