One thing I've come to believe

Dogs don't have the capacity to sit there and wonder "when is he coming back, why am I alone, I feel so sad, Oh-please come home soon". That doesn't mean when you come back he won't explode with excitement. During one's absence I think the dog is just in blissful acceptance and is just as excited upon your return whether it's a week or 20 minutes.

At least I hope its like that.