MWS A fanfic I have never finished included pony Rainbow finding out that human Applejack and Rarity are dating and _*not_* being able to easily see pony Applejack and human Applejack as separate people. Or at least if the other Applejack is dating Rarity, _*her_* Applejack must share the same feelings.
Applejack doesn't get why she's so upset, since she sees the human Applejack as just another member of her large extended family.