Why do we meet people during our journey of life? Some of which we like, some we don't.
Those whom we don't like don't bother us when they leave, probably we feel happy. But what about those whom we like....
It is then we feel pain, sadness, loneliness, dejected etc etc.
That is how we come to understand the theory of 'role play'.
We all have a particular role to play in each other's life. Whether it is parents, sibling, friend, lover, spouse, children, grand-children, neighbour, employee, employer, teacher, student etc. Whatever name has been given to the various relationships we experience in our lives we play a particular role. We learn some, we teach some, there is mutual give & take and that is how we grow.
We all act as a medium, instruments in the hands of God.
It is said in Bhagwat Geeta that we should keep ourselves away from craving and aversions, in which this role play theory proves helpful.
It helps to keep ourselves centered rather than getting swayed away in passing emotions.
Now it depends solely upon us how well we play the roles given to us
God is watching :-)