I think this is what happened after Royal Wedding episode, it may looks like happy ending, but in that episode Twilight almost lost her brother, her friends abandoned her, her teacher showed huge disappointment in Twilight as well as big lack of trust in her student, then after traumatic experience with being imprisoned in cave, her mentor being defeated and then fight again hundreds of changeling's.



And after this all, the only Pony who apologised was Applejack, and now after the wedding is over, Twilight is crying away from her friends so no one would see her on her lowest ( she is sad but not want to ruin her friends fun ).