Promises We Break after Dark by Rachel Higginson

Ada Kelly is doing the best she can. Smart, driven, and practical, she works hard to make her favorite Durham bar, Craft, as successful as possible. Except she’s thwarted at every turn by the sibling drama of the bar’s co-owning trio. Still, she loves her job, and everyone she works with.
Well, almost everyone.
Charlie English is selfish, flakey, and the sexiest man she’s ever known. And he makes her absolutely stupid. Early on in her employment at Craft, Ada made the mistake of sleeping with him. She knew it wasn’t going to go anywhere. Charlie wasn’t the kind of guy who knew how to settle down. Or think about anyone besides himself. So why had she done it? And why would she still do it now? Years later?
Ada has promised herself she’ll never make that mistake again. She’s promised herself she’ll put Charlie in the past where he belongs and move on with her life.
But the thing about promises is . . . they’re meant to be broken.