The Guardian by Nicholas Sparks

Since her husband's tragic death fours years before, 29-year-old Julie Barenson had been reluctant to date, but now feels ready to test the waters. Soon, she is being wined and dined by Richard Franklin, a handsome and sophisticated engineer who treats her like a queen. She also suddenly finds herself entertaining romantic thoughts about Mike Harris, her best friend in the world. Mike is nowhere near as debonair as Richard and has permanent grease stains on his hands from his work as an auto mechanic, but he's funny, loyal, and a great favourite with Julie's beloved dog Singer. When Julie innocently chooses between the two men, she has no idea that she will set off a chain of events at once terrifying, dangerous and, ultimately, deadly. A riveting tale of love, jealousy and obsession, THE GUARDIAN has all the romance that Nicholas Sparks' fans have come to expect as well as a new element of suspense that will keep them turning the pages late into the night.