I believe that we desire others from a sense of mystery. Ril notes this in her originating node, where she wonders what a person's lips would feel like pressed against hers. When the mystery or illusion is disturbed, the magic is gone and we feel a sense of loss.

Sometimes desiring is actually better than having. You can have a desire for a beautiful woman you've never met (such as a movie star, singer, etc.) without the intrusions of everyday life pecking away at the magical facade we've erected for our own pleasures. I think that a guy who desires Pamela Anderson, for example, isn't thinking of her wearing an old flannel bathrobe picking up the trash that the dog just knocked over. He's thinking of the mystery he's built around her, what it would feel like to hold her, and more.

I've been married to a woman I desired in high school. We were close friends, but we never went out. I built up a huge dreamscape for us to live in inside my cranium, as is the way with oversexed teens; but it was more than sex. We ended up getting together years later, and in my case the desire I built up was nothing compared to the reality. I was lucky, and she's still the woman I desire most, followed by Milla Jovovich.

The desire is what keeps us young.