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.
Twilight Sparkle is sure that Rarity and Rainbow Dash are having relationship issues, primarily because they keep inviting her to join them on all their romantic dates.
Twilight finds it a bit difficult to reconcile Celestia's playful new manner with the regal teacher she knew for so long. Once she does, however, the benefits are plain to see.