I must have a twisted mind because I rather enjoyed the premise of Among the Ten Thousand Things, which features a jilted lover sending her entire correspondence with the man who dumped her to his wife. Sadly the box is opened not by the wife, but by her teenage children (I did not like that part!) and nothing good comes out of that.
So the book is really about a marriage blowing up, and it seems we have read many such story. The author structures the story cleverly but it was pretty boring, to me.