I see it could be two ways. One: the big dog is very kind and left the big bed for the pup. Two: the pup went on the big bed and left the small bed for the big dog. In that case, if I was the big dog, I would just lay on the small dog (or around it).
My dog died of cancer 2 weeks ago; my cat misses him. This story is heartbreaking, but it's true love at it's highest. Wow sad an beautiful what a great story animals are truly amazing. (After reading this sweet beautiful story, I can't stop crying***)