Vital Temptations by K.L. Lewis

After falling in love with a fellow pediatric resident, Dr. Bethany McNeal is devastated to discover he's married. Unable to escape her feelings when he reenters her life, Bethany tries to move on with another man—but the past refuses to stay buried. Torn between desire, truth, and the life she thought she wanted, she is forced into a series of difficult choices that will change her life forever.