[Psychological tag is also something I wanted to mention.]
Through all her lessons and all her adventures Twilight has learned that the sacred gift of friendship is one of the most important things anypony can have. So when she decides to bestow this gift upon another, it is only reasonable to expect good things to come of it, right? But is too much of a good thing inherently bad? Is there a point where a friend is too good of a friend to comprehend or accept? How can the Princess of Friendship hope to deal with a problem where the very aspect of friendship is her greatest disadvantage? How can she hope to overcome a system where every act of kindness, is a mistake? And how can she possibly hope to defeat an enemy, who is arguably her greatest ally? How can she manage to end the obsession?