Humans do things like crying or ‘moping around’ when we are sad or depressed. Children will throw tantrums when they are sad. In many cases, we just assume that canines have the same set and spectrum of emotions like we do.
Yes, dogs sense when you are sad and are usually very aware of most other emotions. They can tell when we humans aren’t feeling optimistic, out of sorts, or downright miserable.
Our dogs sense sadness because they can sense the changes that occur because of it. Your dog is constantly watching you for even the slightest visual change. They are always reading our emotions, constantly tracking our movements.
Your dog might become upset when you cry, but not sad from a human’s perspective. It’s possible that dogs learn to approach crying people because their owners give them affection when they do.