This is not an easy topic. Two Married men (Nate and Andrew) with children & who are also neighbours, fall in love and start cheating on the missus. 
 I find it courageous to write about that, and I praise the author for choosing this topic. 
 This said, I do not think it was that well written. The characters development was not polished, many times characters behaved in ways that did not look like them at all. And generally the plot is great, but in the details, it is not well executed. as a consequence, some important parts of the plot felt forced. 
 And without giving any spoilers, I would say the relationship between Nate and Gary did not make any sense at all. 
 However, I think this book is OK, and could have been very good.