Sweetie Belle moves from Ponyville, because of one fateful turn of events.
She runs away from something.
And the big city of Manehatten is her place to hide.
One of her friends welcomes her there.
A friend she hadn't seen in a while.
A friend who had made the same bad decision.
Well, it's not one of the best stories I've seen but I have very high standards. This is fine. As you said yourself, we need an explanation for how Sweetie lost her horn. And I believe you would benefit from an editor.