Kingdoms: the Fallen Oak

This world is separated by elements. There is the earth kingdom, water kingdom, fire kingdom and air kingdom. Each has it's own rulers and it's own territory. The kingdoms are completely equal, but secretly each royal family believes it should rule over the entirety of the world. They all think they're better than each other. But nobody expects any real violence out of the delema, until the prince of the earth kingdom is almost assassinated on a train to his betrothed in the water kingdom. Nya witnesses this. She just got a job as a freelance guard, but she now finds herself stuck with the prince, alone in the wild avoiding assassins. Her duty has now become an impossible mission to deliver the future king to the water palace safely... but what happens when he no longer wishes to fulfill his alliance. This is a fantasy story about love I'm the strangest places. Full of betrayals and surprises, book one of the kingdom series should keep you entertained.