This is a Harlequin Medical Romance book. Here's the summary from the back of the book:
Registrar Alyssa Ward is not pleased when she wins a date with the E.R. consultant, Honorable Sebastian Radley. She's not in the market for a relationship---especially not with a renowned womanizer like Seb. But, then again, he is devastatingly handsome---and, after all, it's only one date.
Seb has never been one for monogamy. So why does he find that one date with Alyssa just isn't enough? There's so much more to her than just another woman he's dated. And when she gives him some life-changing news, he finds himself reassessing who he really wants to be---every woman's honorable playboy, or Alyssa's honorable husband?