She felt happy among her family.

In the context of family and relationships, it refers to being in the company of others or surrounded by them.
He is popular among his friends.
They shared secrets among themselves.
There was laughter among the children.
among friends
among family
among peers
between
in the midst of
surrounded by
The cat is among the flowers.

In the middle of a group or surrounded by others.
She felt happy among her friends.
The treasure was hidden among the rocks.
He stood among the crowd.
among friends
among the trees
among the stars
between
amid
in the midst of
She felt happy among her friends.

In the middle of or surrounded by a group of people or things.
The cat slept among the cushions.
He found his keys among the papers.
They shared stories among the group.
among friends
among the crowd
among the trees
amid
in the midst of
surrounded by