It is an interesting observation in life that every disappointment leads one to a new hope.
Hegel, one of the modern philosophers would speak of a process of thesis, antithesis and synthesis as the cyclic process on which carries on in the world and in its history.
It is also true in the case of disappointment and hope. It is clearly understood in a political context. When we elect a new government everyone has the hope that they will do the best for the people but often they disappoint the people. However, in the next election we elect another group with the same hope.
So the rhythm of disappointment and hope is carried on life.