I think I have a decent understanding of the psychology of relationships, and it is clear to me that most human beings exist in a state of inward deficiency, and live "quite lives of desperation," to borrow a few words from Thoreau. Those of us who go to college acquire knowledge, learn all kinds of things, but nothing that contributes to our growth as human beings. When I take a deep breath and look around me, I see that our entire world is a product of people seeking self-fulfillment through external means. Like the doctor who works hard for his degree, then longer and harder to get a bigger house, a faster car, all the trappings of wealth that are an imitation of a beautiful life, the acquisition of which takes up all of his time - then he wonders why his wife is unhappy. Is he not giving her a good life? Is he not working himself tooth and nail for her? If he knew how to ask her, and if she knew how to tell him, she would say that she does not want things, she wants him. She wants a husband who nurtures her emotions and cherishes her, and he wants her acceptance. His quest for more and more things would end if he knew, really knew, how much his wife actually loved him, and that she accepted him just the way he was. If your interested read Men are from Mars, Women are from Venus for more on relationships, but my point is that this outward-seeking fulfillment is a universal aspect of mankind across the board, in every nation and every society.
Humans are motivated best by fear. Within every man is a boy who needs to be accepted, and within every woman is a little girl who needs to be cherished - this is a fundamental aspect of what it means to be human. Take into consideration the fact that most of us never completely feel either of these things, that we are all motivated by the fear of lacking these things, and it explains much of human behavior - the way that societies, nations, religions, governments, media organizations, and individuals react towards the world, each other, and their group/self-aspect. The root of all hatred and prejudice is a lack of inward self-fulfillment. When you feel loved, accepted, cherished, there is no hate in your heart - there is not even the potential for hatred within you because hate is the projection of our own inadequacy upon another. There can exist anger at injustice and at the mistreatment of others, but hatred is literally impossible when you are a complete human being.
I am only beginning to truly understand what it means to be human, but I definitely recognize that we are all afraid of not being loved - no matter how beautiful someone is, that fear is still very real. Henceforth come the distractions: the books, the television, the wars, the toys, the attempt to become more because you yourself are not enough, and the investment in that which is other than yourself - your governments, your religions, your beliefs - all things in which you have a real, personal investment. And when someone threatens that investment you must mitigate that individual, you must hurt them, you must destroy them, because they are threatening a part of you. This is why humans kill each other over ideas.