While the phrase "Happy Ending" often refers to a generic story trope where "they lived happily ever after", it is also the title of several specific creative works. Depending on what you are looking for, here are the most prominent "Happy Ending" stories:
This is a famous metafictional short story often studied in literature. It provides several different scenarios (labeled A through F) for the lives of a couple named John and Mary: The Happy Ending
Widows or divorcees finding companionship later in life. While the phrase "Happy Ending" often refers to
The "perfect" life where they marry, have children, and die of old age. and die of old age.