second: i'm watching more "sex and the city" on hbo on demand and it prompted me to google some theories and ideas. in my search, i discovered this, which i thought was interesting:
According to Dr. Crenshaw, oxytocin may indeed be the reason why women more than men tend to be "love junkies" or "the slaves of love."
Oxytocin and estradiol synergize to produce heightened sensitivity to touch. Apart from that, Dr. Crenshaw points out that little girls tend to get more cuddling, which generally produces a considerable degree of pleasure regardless of estrogen levels; as the girl gets older and parental cuddling gets less, she may suffer from oxytocin withdrawal.