Fluttershy was experiencing some changes in her that she didn't know what to do about. Due to fear she went to the only friend she knew that could help her. That's when things escalated and curse emerged, threatening to eliminate ponykind.

Ps: The ponies in this story have human features, like hands, breasts and can stand upright on two legs. However, they are still ponies with manes, coats, tails, etc.