Choose Me by Tess Gerritsen and Gary Braver

 Jack is a Boston college professor married to physician Maggie. They've been happily married for a dozen years and still love each other, but Jack is becoming dismayed at the long hours Maggie has been putting in at work. So when a beautiful and brilliant student named Taryn shows up in one of his classes (on star-crossed lovers no less) and develops a huge crush on him, he is more tempted to stray than he otherwise might be.  When Taryn ends up dead (which happens in the first chapter, so I'm not giving away any spoilers), the cops first think it's suicide, then they begin to wonder.

My favorite characters in this book are all women: Maggie, Taryn's hardworking mother, and Frankie--the single mom cop who is assigned to the case and who first wonders if there is more to this case than meets the eye.