During the early elementary years, children develop a strong sense of identification with their same-sex parents. They begin to mirror their parents, including the affection they see taking place between Mom and Dad. These are the years of the first crush, of puppy love. It's when we all begin to try to figure out the mystery of love.
It doesn't last long. By the third or fourth grade, boys are playing with boys and girls are playing with girls. During these middle childhood years, it isn't "cool" to have a close friend of the opposite sex, much less a romantic interest.
Sigmund Freud called these the latency years. He explained that "Eros," the sexual force, was repressed during this stage, as boys and girls bonded with their same-sex peers.
But Eros returns -- strongly -- at around age 13 or 14. Driven by a chemical blitzkrieg, young teens engage in all kinds of courtship rituals. This is an awkward, self-conscious time for children. The two most compelling motives in their lives are a need for acceptance and a fear of rejection. Being able to attract a member of the opposite sex means you're OK. The more popular your boyfriend or girlfriend, the more status you acquire.
Later, around 17 or 18 years of age, kids develop the capacity for true intimacy. The selfishness that typifies boy-girl relationships during early adolescence gives way to greater self-assurance and, therefore, greater capacity to recognize and respond to the needs of others.
Physical attraction still counts, but it becomes less important than personality. Trust replaces status as a prerequisite for love. Finally, for most of us, love becomes a verb.