Some thoughts I had on the subject while in Psychology class.
We all have needs, which are states of cellular or bodily deficiency that compel DRIVES. DRIVES are perceived states of Tension that occur when our bodies are deficient in some need. Our drives are simply psychological urges to relieve that tension. When we need food, we feel the tension of hunger in our stomach, which DRIVES us to eat. When your bladder is full you feel that tension in your gut and you just have to let 'er rip. The greater the tension, the greater the URGE to relieve it.
Since reproduction and companionship is another basic human need, the purpose of attraction is simply to present yourself as someone that can satisfy that need. The awakening realization of this unmet need will give her a feeling of tension that can only be relieved by YOU. She also has to perceive a "loss" in your absence. When your actions are guided by this Mindset, it's easy to be the prize. It makes sense from this perspective to give without expecting to receive in return.
Why do so many people look to Christ? Because he provides relief from the perceived tension of guilt, and the terrible pain of paying for our own sins. We provide no value to him (he doesn't need us in any way) but he provides all the value in the world to us, and billions of people adore him. This is useful to know for everyone, whether you believe in Christ or not. I guess the point is (before I ramble on anymore) to be the one that can provide for the social needs of others (male and female alike), and they will feel the urge to be in your presence.