Every Vow You Break by Peter Swanson

After Abigail has a one night stand on her bachelorette weekend, she wonders if she should tell her fiancée Bruce or keep it a secret. She decides to not confide in Bruce, but when the guy, Scottie, appears in New York City right before the wedding, Abigail is on high alert. Abigail and Bruce marry and honeymoon on a small island in Maine that Bruce has chosen. Then Scottie shows up on the island and Abigail wonders what is going on. Every Vow You Break is an unputdownable novel that will have you turning the pages to figure out what Abigail has gotten herself into.