Complex sentence: He has done their photos for years and, over time, has developed an obsession with the family; he idolizes their happiness and affluence, memorizes every personal detail about them that he can learn, and finally begins to associate to them more and more.
Split into simpler sentences: He has done their photos for years and over time, has developed an obsession with the family. He idolizes their happiness and affluence, memorizes every personal detail about them that he can learn, and finally begins to associate to them more and more.