A Dragons Mate

Many people believe that Werewolf and Vampires are the only ones that have mates. Little do people know that there are dragon people.
They shift like werewolfs but stay hidden and out of sight like vampires. They are just considered dragons.
They have been separated into the two big groups of the community, dragonlights and dark reigns. For years the dragonlights have hated the dark reigns for what they had done to them years ago. When the prince is desperate and looking for his mate before he is crowned king and shifts, he runs into a little problem.
What happens when he realizes that she is a dark reign? And a old enemy emerges to take back the land that was taken from his people long ago.