Bound By Knighthood by Nicki Chapelway

An academy in the sky,
Two rival knights-to-be,
And the cursed princess who could destroy them all.

Willow is a fae born with a weak and muddled magic. In a world where magic can be bought…for the right price, she attends the Academy of the Gilded Knights. Her goal: to swear her service to a high fae in return for powerful magic.
There is only one person standing in the way of her success, Byron Coalbiter, her childhood rival.

A blacksmith’s son born with a magic far more powerful than her own, Byron has always lived a seemingly charmed life. But apparently that isn’t enough, because now he’s looking to steal Willow’s knighthood.
However, there is something sinister taking place at the academy, and the princess they both rescued might be far more than a damsel in distress. She could very well be their undoing.

If Willow and Byron want to save their precious academy then they are going to have to put aside their rivalry, move past the strange attraction that they feel toward each other, and learn to work together before they both lose their dreams.