And they lived happily ever after...
The next morning, she looked over her shoulder and realized her Siamese twin was dead.
Interpretation: It is a naive fantasy to believe that people live happily ever after–happiness does not behave in that way. Happiness is fickle and does not owe you anything.
One moment you may be happy, and the next you are sharing rigor mortis with a clump of cadaverous meat and a contorted, pallor face staring blankly back at you.
It is ok to be unhappy–it is part of the absurd order of things.