Suzanne's Diary for Nicholas by James Patterson is a romance. Suzanne writes a diary of how Nicholas's parents met and most days of Nicholas's life. Katie is the first entry of the Diary. Katie has the diary because Matt, Suzanne's husband and Katie's lover, gives it to her. Katie had thought that Matt had been ready to propose to her. She had had a special dinner ready and had two surprises for him. His volume of poetry was going to the printer with more prints ordered than usual for poetry. Katie has been Matt's editor and they are both pleased with this. Katie had been going to tell him that he would soon be a daddy. When Matt had come, he learned about the poetry book and saw the table and left Katie before she could tell him about the child. The entries go on with Suzanne telling all the romantic and intimate things about Matt's and Suzanne's marriage. The reader isn't sure whether Matt has been cheating or his wife is really dead. Suzanne's entries are long and detailed with romantic bits about Matt and herself. She tells of Nicholas's birth and his daily activities. She describes the wedding and then the christening. It is obvious that this is the perfect marriage. Could Matt be cheating on Suzanne yet act so in love with Katie? Katie's entries involve her hurt and her questions. The reader is given a view of her home life and the support that she has received from her parents all through her life. While the reader knows she is hurt, the reader can also predict that she will go on with life and make the best of it. Katie has friends in the city who support her. Two of them had been to the doctor with her when she was checked for the pregnancy and were the first to hear that she would not abort the baby.

Near the end of the diary, the reader is given one entry by Matt. First he tells us that Suzanne has died from a heart attack. Matt is sitting in his son's room and talking to him. Finally as Matt reaches for the crib, he tells about patting the baby that is not there. Nicholas and Suzanne had died when Suzanne had a heart attack while driving. After reading that entry, Katie goes to find Matt. She visits Martha's Vineyard where Suzanne and Matt have lived. Matt has disappeared from the island. Katie does learn a bit about him from his neighbors. She returns home. Finally, Matt comes to her. They come together to get married and the reader knows that Katie will help him heal.