A Perfect Stranger by Danielle Steel

After the collapse of his first marriage, Alex Hale fears he will never find happiness again. Young, rich and desperately lonely, Raphaella is sentenced to an empty life in her mansion, bound by a sense of honour and duty to her elderly husband. Alex and Raphaella are worlds apart when life conspires to bring them together. But theirs is a love affair of stolen moments and the promise of tomorrow. Is it possible to find happiness with a perfect stranger?