There are lies amongst friends and families, and they always hit the one who is lied to the hardest. Shining Armor is that victim, and now he wants nothing to do with them. He, especially, wants nothing to do with the mare he married.
There really is not much to say, except I am here for the same reason I write on Fanfiction. I want to entertain you with my writing, not just detail it but make you feel that you are in the story.