Childhood - maynot be the best butnit is the happiest phase of life for most.
Married - this phase will make you to realize the purpose of your existence.
Unmarried - you will feel loneliness at some point.
I agree with you very much. It is true that childhood is the happiest time for me. When I become an adult, I begin to realize the responsibilities that I need to bear, and then I know that the happiest time has passed.