Luna lost a long standing bet to Celestia and now she must pay up. Twilight is not thrilled and thinks that giving Celestia a stern lecture will save her marefriend from a terrible fate.
Since becoming marefriends with Twilight, Princess Luna has been more cheerful, more cheerful than she has ever been. This brings about suspicion from Celestia and causes her to want to figure out why her sister is suddenly so happy.
Princess Luna has always been the one to hide her feelings and try to not show signs of weakness but something has been troubling her heart recently. After raising the moon and going out for a flight, she decides to visit Twilight for some advice.
Celestia and Luna have both fallen for Twilight Sparkle. So naturally the only way to fight for her love is to make themselves normal! At least, as normal as two princesses can be.
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.