"And they all lived happily ever after."
Cadance believed that was true when she was married. A princess and her knight in shining armor, just like in the fairytales. Their true love had defeated the evil Queen Chrysalis just like in the fairytales. In short, Cadance felt like she was well on her way to her own happily ever after.
However, as an alicorn she is immortal. One day she will be forced to outlive her beloved stallion, and her happily ever after will die. What will she be then? The Princess of Love without her beloved?
No, that cannot happen.
But there is a pony who has cheated death a number of times: King Sombra.
With his help, Shining Armor too can become immortal, and they can both live happily ever after, together forever.
Right...?
This is not a shipping story. There are romantic themes, but it is not the focus of this story.