A Witch's Guide to Fake Dating a Demon by Sarah Hawley

Mariel is prophesied to be the most powerful witch seen in centuries, but she prefers baking bread to brewing potions. When a spell goes very wrong, Mariel finds herself staring down a demon - one she inadvertently summoned for a soul bargain. Ozroth the Ruthless is a legend among his kind.

But ever since a bargain went awry, he's been a laughing stock. A deal with Mariel could earn back his deadly reputation. However, getting Mariel to sign over her soul is going to be a lot harder than he anticipated.

Ozroth can't leave her side until she makes a deal, and becoming awkward roommates quickly escalates into real attraction. But Ozroth is running out of time - and if he succeeds, he'll damn Mariel and their chances at love in the process.