It's been almost over half a century since the bearers of the elements of harmony defeated nightmare moon. Since then, times have changed. Age has snuck in, for all six ponies.
No, all five ponies.
Being the alicorn ruler of Equestria, Twilight has watched her friends grow old whilst she stays youthful.
Today, the last one of her friends was buried, and Twilight has had enough.
Prequel to https://www.fimfiction.net/story/482796/hello-again