True, sharing happiness increases the happy moments in life and makes them outstanding.
While I would like to add that being happy just on your own also is a thing. Even to make oneself independent to have to share this moment. It is liberating, I think.

Happiness is already real when you feel contend when looking at a peaceful nature scene or being just satisfied spending time with family. This happiness is felt and sensed by others and in this way, there is no further need to emphasize it. It's shared by its own:)