The Billionaire's Obsession: An Enemies to Lovers, First Time, Office Romance (Billionaire Brothers) by Penelope Ryan

He’s filthy rich, infuriatingly arrogant … and completely obsessed with her. Aiden King always gets what he wants. As Seattle’s most notorious tech billionaire, he’s built an empire with charm, money, and zero apologies. Women? He doesn’t chase them—they fall at his feet. Until her. Lilly Richards is smart, stubborn, and shockingly uninterested. She’s running a youth nonprofit, not auditioning for a spot on Aiden’s arm. But when he’s forced to shadow her at work, their chemistry turns combustible. She’s never given herself to anyone—never trusted anyone enough. He’s a player who’s never wanted someone more. Now the bad boy billionaire is hooked—and he’ll do anything to make her his. Even if it means losing his heart in the process. Read more