At the Canterlot Wedding the changeling threat was repelled by the power of love.
However, the changelings are recovering, and will soon attempt another invasion; it's up to the Elements of Harmony to keep them from doing that, and it's up to the Royal guards to protect them until then.
Follow Whinnyam Blueblood and Gleaming Blade as they nearly fail at that.

May be cancelled because it hasn't been fun to write and it doesn't seem fun to read.
I have learned that you should plan your story in detail in its entirety before you begin to write chapters, and that the subject I picked was probably too complex for a beginning writer.