Haunting Adeline (Cat & Mouse #1)

The book is about how Adeline forms a “relationship” with her stalker while she discovers who killed her great-grandmother (who also had a stalker), while from the stalker's point of view, he is looking for an organization that kills children while stalking and searching. as Adeline falls in love with him. 

This is book number one in the Cat and Mouse Duet series.