It should not just be assumed that Jed suffers the syndrome, but it is imperative. Erotomania, or de Clerambalts syndrome was invented by the author and since then has been adopted by psychologists. In actual fact it has caused some outrage amoungst the psychology community because the last chapter which explains in some detail the symptoms, history, etc. was actually written by McEwan.
Clarrissa believes that Jed is real, she has met him at the accident, but doesn't believe that he is following Joe, her idea that Joe is going mad is however quite rational, although Joe is right about Jed harrasing him, his obsession with Jed is very irrational. He has broken his typical daily routine, is overcome with thoughts with him and gets paranoid to the point of ruining the relationship between him and Clarrissa; this obsession over Jed greatly reflects the obsession Jed has for him.
Joe believes only what is tangible, and Clarrissa, finds truths in places where evidence is not possible, but further into the book in an arguement between Joe and Clarrissa these roles are reversed and it is Clarrissa who is asking for evidence 'have you actually seen him', and it is Joe who delves into a more delerious state and starts looking for possibilities into what isn't neccessarily there.
An area which is difficult to steer away from in the essay writing is who's reality is right and wrong, what is neccessary is to understand that all of the characters provide a different view to the events happenening around them. You need to be able to explain what their reality consists of, what drives it and possibly what are the fundimental causes for the changes in it.
Again, another thing to remember is that the book is written entirely from Joe's point of view, the chapter which is supposidly from Clarrissa's point of view is infact Joe recounting what she COULD have been thinking, it is his interpretation, not hers.
Jed's love for Joe itself, to me anyway, is not a major part of the story, but rather the effects it has, the obsession, and who else does he love. I believe that Joe is only Jeds second love, and that his first is that of a greater power, a god. Unlike Joe, god doesn't reject but excepts him, due to Jed's fantasy god is whoever he wants him to be.
Anyway I hope some of this helped, i think Enduring Love was a brilliant book, if slightly disturbing and confusing in places and i hope u get alot out of it.
