Undertow by Kathleen Lawless

No Promises.
No Regrets.
That’s the Deal.

Cassidy has been waiting years to get revenge for the way Sloan broke her teenage heart. And here’s her opportunity–to make him fall in love with her, then dump him on his well-shaped derriere before he knows what hit him.
Sloan can’t believe his luck. Stuck on board a cruise ship for a family wedding, Cassidy makes him an offer he’d be foolish to refuse–to be her lover for their week on the ship, no strings attached.
Then they discover the ship’s special suites, where guests are encouraged to indulge every fantasy.
By the time the boat docks, it’s difficult to know what’s real and what isn’t, let alone walk away.