Are dolphin really happy and friendly to human?

Description

Dolphins who can live upto 20-30 years in their natural
environment, suffer a great deal in captivity leading to a
massive drop of about 50% in their life expectancy. The
dead dolphins are silently replaced with new ones,
basically without making it public
People often perceive that Dolphins smile, which means
that they are happy. However the dolphins smiles are
nothing more than the anatomy of their jaws which
creates the illusion of a constantly happy and friendly
creature. They cannot help but "smile" whether when
happy or sad.
We are often told that they are friendly creatures and
squint when happy.
However, the fact is that different chemicals especially
chlorine, used to disinfect the pool water, often irritates
or burns their eyes, causing them to squint or often swim
with their eyes closed.