Entrance by J. J. Sorel

When Clarissa starts working for billionaire Aidan Thornhill, the last thing she expects is romance. Aidan Thornhill is a self-made billionaire with a mysterious past. Fighting for the Special Forces, he returned years later with bad memories and a million dollars gifted to him by a dying soldier. Now, he’s one of LA’s wealthiest bachelors—and he’s also smoking hot.
One steamy night on his yacht, he seduces Clarissa and when he discovers her inexperience, instead of running, he takes control.
Aidan’s dark past soon places a wedge between the insatiable lovers when an ex-army pal, and a rich spoiled society girl with sharp claws stir trouble.
But he’s determined to have Clarissa even if it means putting his life in danger, while she must choose whether to ignore the rumors or leave her dream job.