It is obvious that expectations decrease happiness when those expectations are not met, but expectations also decrease happiness when they are met! How? Expectations undermine gratitude, and gratitude is a key element of happiness.
When the husband “fully expects” his wife to prepare a hot meal every night, the husband feels less grateful, less thankful, and less appreciative when he gets the meal, because, after all, he expected it!
If, on the other hand, the husband avoids “expecting” the hot meal, he will have profound gratitude for his wife’s efforts in preparing hot meals each and every night of their 60 year marriage.
When we give Little Johnny too many privileges without requiring that he somehow earns those privileges, then we create expectations in Little Johnny, and inadvertently deprive him of the ability to be happy by robbing him of his gratitude.