Hard and Fast by Mari Carr

Penny is tired of being seen as the gamer, the crazy cat lady, the mom-jeans-wearing, YouTube-bingeing, quirky IT girl. She’s barreling toward 29 and ready to make some changes…in her appearance and her nonexistent love life. But she’s smart enough to know she needs help—and who she needs it from. Her billionaire playboy boss, Gage Russo.
Bachelor Gage’s life is typically full of excitement, on the work front and in the bedroom. He’s never lacking for female company and he rarely sleeps alone. Regardless, lately, he can’t shake feeling bored. That is, until Penny challenges him to a friendly wager…one he promptly loses. Her prize? Lessons in seduction—from him.
Lines get blurred as Gage pushes harder…moves faster…teaching Penny things she’s only ever fantasized about. But the playboy with all the smooth moves makes one big mistake when he fails to tell his sexy student that the lessons are no longer fake, and what he wants from her is very, very real.