It makes immediate sense that our happiness depends on our ability to connect; we are most unhappy when we feel isolated. But it takes skill to connect, skill we often lack.
It takes more skill to connect with human beings than with dogs, not only because dogs are simple and always happy when we arrive, but because we do not see them as competitors. They may kill our neighbor's puppy, piss on the carpet, run away and cause an accident that costs us dearly, but we love them anyway. We know that they don't know any better. We don't expect too much. We do not cling. We can forgive.
It does not take very much for us to disconnect from another human being. They may just look different from us or utter one wrong word and viola, we reject them. We expect close to perfection and cling to our every expectation. We are convinced that they know better, or could have known better. We cannot forgive them.
We cannot be a Mensch when we see only the competitor in the other. Up and foremost we are all sentient beings, made up of water and carbon. Up and foremost we are all living on this planet Earth in a universe that gave birth to us against all odds.