why do fairy tales have happy ending

I think just the first part of fairy tales is mirror of life, because it reflects the reality in society : the good people often suffer the loss dued to their low social class or their sad plight. The aim of each tale is to encourage them to continue their dignified life, as the angels are always on the side and bless them, so they will touch the happiness in the end.

Fairy tales are usually made for children. Maybe in someways they are created to put into the mind of the young ones that life is full of surprises and that a good heart will enjoy a happy ending story. As I observed fairy tales main focus is the conflict between good and evil, and that the good always win... the good will then be rewarded with a happy ending story. But sometimes children might misinterpret the idea that there is always prince charming, that when they grow up they might think that having a partner has no difficulty because prince charming has never been a bad guy... so when problem arise they don't know exactly what to do with it... ending then into separation.

I believe fairy tales have happy endings because little girls doesn't like sad endings, right? And they would want happy endings because they will feel sad if the ending is sad. And I don't know if fairy tales are mirrors of life, but I know there are happy endings, we just need to be positive.