archetypal fool

Well, I understand that this is meant to be a philosophical discussion of love, but speaking through the window of biology and evolution, it's easy to see why love might have evolved, and why we feel so strongly towards certain people in our lives. By looking at it in this way, the question might be easier to answer.

When we become emotionally attached to somebody, we tend to describe it as love, but according to the context of the original post, I assume the question is where does love for an individual not related to us originate, as opposed to where does the love we feel for family members come from.

If that's the case, then love is the ultimate solution for avoiding a situation where unregulated polygamy would have a negative affect on the population. To paraphrase a section of The Selfish Gene by Dawkins: If you've got a population entirely composed of polygamists, such that each individual will mate and move on leaving one parent to raise the offspring by itself, the offspring has less of a chance of surviving to breed than it would if both parents had remained to raise it. In such a scenario, any individual which somehow becomes inclined to stay with its mate and raise its children cooperatively will increase the likelihood that its offspring will survive. Of these surviving offspring, half will contain the genes of the monogamist, and so, given a few generations, that gene will spread thought the gene pool.

With this in mind, it's easier to rationalize love and understand what positive affects it has on individuals. That's why you feel happy and fulfilled when you find your soul mate, and that's why every individual needs love to function properly. It's a testament to how beautiful and powerful life is.