The human versions of Applejack and Coloratura met at Camp Friendship all those years ago, but unlike their pony conterparts, they remained in touch. Now years later Rara is making it big in Manhattan and has lost almost everything that made her Rara in the first place.
Essentially, Coloratura/Applejack romance as Rara navigates fame after she breaks away from Svengallop. Not exactly a mirror of what we saw in The Mane Attraction, but kind of similar.