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.
In Luna's day, lovers wooed one another with splendorous poetry, beautiful songs, fancy dinners, and flowery niceties. But to gain the affection of an unconventional mare, she's taken steps for an unconventional confession.
It seems like an easy choice, doesn't it? However, when you've spent a thousand years away from other ponies, the darkness can be comforting. It will take a lot of work to drag Luna out of the darkness, but one pink pony is up to the task.