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.
Based on DarthLink22's "About Last Night": Celestia has seen the wedding video, and summoned Twilight Sparkle and Applejack to her quarters to discuss the matter...
Twilight and Minuette are perfectly happy and just want to be left alone. Unfortunately, Ponyville is particularly prone to mysteries and disasters, and -somepony- has to deal with the mess.
Golden Harvest isn't jealous. Sure, her neighbor has glamor, adventure, friends and firm, toned flanks, but she isn't jealous. Nope, not jealous at all.
Cheerilee has been secure in her sexuality all her life, but when she finds out that it was actually Fluttershy of all ponies that was singing with the Ponytones, everything that she was sure of is suddenly thrown into doubt.