I believe this romance doesn't have a definitive conclusion nor a stereotypical life lesson to extract from.
This is the portrait of an empty man who shits in the concepts of morals and pre-defined social behaviours.
It is composed by a series of disjointed introspective thoughts of someone seen as a lunatic by society.
If there is anything that somehow represents conclusion is that rationality is absolutely meaningless to a morally ambiguous society who in its eyes assumes that not being affected by his mothers death by natural causes is far more repulsive, far more ''evil'' than killing an arab man in cold blood with gunshots deliberately.
It is a good book