Why Women Talk
"Talking releases a rush of dopamine and oxycotin (the 'reward' and 'bonding' neurochemicals) in a woman's brain," explains Louann Brisendine, M.D., author of The Female Brain and a neuropsychiatrist at the University of California at San Francisco. "It's the biggest neurological reward a woman can get besides an orgasm." First of all, this chemical reaction explains a great deal about women. Second, it gives you a powerful tool: A simple "I can't wait to see you tonight" is enough to distract her from the insanity of the day and reinforce the love circuits in her brain.
I suspect that like a lot of gender science, this one is on shaky ground. But it does explain a lot.
(From Wife Support. A web article of dubious authority.)