It doesn't appear to have been the happiest of holidays for Demi Lovato and Wilmer Valderrama . The couple are mourning the loss of their dog Spawn, who died over the weekend. Their dog, Buddy, was killed by a coyote over the summer, making the death especially heartbreaking."I miss you so much already beautiful boy," the singer wrote in an Instagram caption alongside a sweet photo of her and Spawn. "When I first met you 6 years ago, I was intimidated by your size and your strong presence. But as I got to know you, I learned you were just one big teddy bear. One handsome teddy bear that's for sure."I'm going to miss the way you greeted me at my car every time I came home or simply when I stepped outside. I'm going to miss the way you were so protective of Buddy and Batman and never got annoyed with them when they were excited hyper puppies. I'm going to miss the way you would nudge at my hand if I wasn't petting you. I'll even miss the way I'd need a Benadryl every time you'd give me kisses just like the way you're giving me kisses in this very picture. All the sneezes, the runny noses, even the occasional hives.. They were all worth it with you."Saying goodbye absolutely broke my heart and I felt as if I was saying farewell to a family member. The only thing that brings me comfort in this situation is knowing that Buddy is probably really happy he now gets to play with his big brother in Heaven. We love you so much Spawn. We miss you so much and we will never ever EVER forget you. RIP baby boy."