It all starts when you 'Expect'

When there is a gap between what you expect from people and what you get from them, unhappiness creeps in.

The gap widens when expectations turn into demands and demands are never fulfilled in a relationship.

You are then left with just two options: 1) Continue expecting from them with a hope that someday your want and desire will be fulfilled 2) Look for happiness within yourself than in them, because when you expect from yourself, you are far more assured and confident to fulfill them.