Charm by J.A. Armitage

You think you know the story of Cinderella…
The kingdom needs an heir and Princess Charmaine is quite aware that the job rests solely upon her shoulders. When her elder sister dies, Charmaine has to take her place at the ball designed to find her a husband. With a hundred men to choose between and her wedding planned, all she has to do is pick one.
Cynder knows about the impending war between the people of magic and those of his masters, but working as an underpaid servant in the palace kitchens leaves him with little power to do anything about it. On one hand, he’s a staunch supporter of equal rights for his own kind, but he can’t deny the attraction he feels for the daughter of the king and queen he works for.
When the two meet, sparks fly and not just the magical kind…