His mother rightful kingdom was taken by Sombra years ago, even before he was born, and even if his father is the “adopted son” of Empress Nightmare Moon, he won’t inherit the kingdom. He is the captain of the royal guard, so at least he has a little bit of authority over something.
He is betrothed to Princess Blood Rosabella, his parents and hers are trying to make an even stronger truce between the crystal ponies and the umbrums…but how can you love someone when you don’t love yourself?