She was his little sister, he just couldn't stand the thought of her being with another stallion, least the Spirit of Chaos and Disharmony. She must be under some type of mind control! How could Twilight Sparkle even think of marrying Discord? Shining Armor would not stand with his hooves crossed while his sister ruined her life, he would do anything to break her free of the "spell". But is she really being controlled, or he is simply jealous?