After spending Nightmare Night in Ponyville, Luna decides on how to reward the six mares who defeated Nightmare Moon and saved her from herself: Marriage.
Celestia and Luna married the mane six, now they have a harem and a honeymoon to deal with. In all honesty, happily ever after isn't all it's cracked up to be. At least there'll be room for orgies.
Have you ever gotten so drunk you forgot you offered the princesses' hoof in marriage to whoever brought your sister back? And how many 'es' there are in 'Princess'?
Cadance has the most wonderful surprise in the world to share with her beloved Auntie Celestia. In fact, it's the most spectacular, wonderful, and joyous news she has ever had to share in her life. Won't Celestia just love to hear it?