Classic Emily Giffin.  I haven't liked one of her books as much since Something Borrowed and Something Blue.  Multiple POV chapters alternate between Lainey, an actor coming to terms with meeting her biological father's "real" family, Hannah, who canceled her wedding after catching her fiance cheating, and Tyson, a DC lawyer who left a job and a relationship simultaneously that were good but not great.   Contemporary literary fiction, characters are 32, they are on a trip together.   College friends, their 4th friend Summer completed suicide after finals their senior year.  The Summer Pact has nothing to do with the season but instead the name of their deceased friend. 

Easy and likable characters, good dialogue.  I didn't feel the chemistry here between the characters but I appreciated their friendship.  The kind of very easygoing adult friendships we all wish we had.  

trigger warning: Suicide, infidelity, alcoholism