This Wild Wanting by Sophie Gonzales

A dangerous bargain. A forbidden alliance. An impossible love. Everybody knows about the faerie market that borders the crumbling edges of the mortal world. It is a place where almost anything can be bought . . . by those willing to pay terrible prices. Skills, memories, years of your life—even the freedom of one’s own mind are the currency of choice. Declan Bonfeld, the only son of a noble house, has never encountered a price he cannot afford to pay. Until the day he attempts to bargain with a ruthless potion merchant for the impossible: a way to bring back someone he loves. When Declan dares to steal from the tyrant’s shelves with the help of the merchant’s captive daughter, Calla, the two discover a horrifying truth. Once a stolen potion is consumed, the thief pays the price, no matter who drinks it. With Declan’s mind and body unravelling piece by piece, Calla must help him outwit her father, the man she has spent a lifetime fearing, before Declan is stripped of everything he is, and she loses the only person who has ever truly seen her.