The Hearts We Sold by Emily Lloyd-Jones

An intoxicating blend of fantasy, horror, and romance-a Faustian fable perfect for fans of Holly Black, and Stranger Things.
Dee Moreno is out of options. Her home life sucks (to put it mildly), and she's about to get booted from her boarding school-the only place she's ever felt free-for lack of funds. But this is a world where demons exist, and the demons are there to make deals: one human body part in exchange for one wish come true.
The demon who Dee approaches doesn't trade in the usual arms and legs, however. He's only interested in her heart. And what comes after Dee makes her deal is a nightmare far bigger, far more monstrous than anything she ever could have imagined. Reality is turned on its head, and Dee has only her fellow "heartless," the charming but secretive James Lancer, to keep her grounded. As something like love grows between them amid an otherworldly threat, Dee begins to wonder: Can she give James her heart when it's no longer hers to give?
In The Hearts We Sold, demons can be outwitted, hearts can be reclaimed, monsters can be fought, and love isn't impossible. This book will steal your heart and break it, and leave you begging for more.