GREY'S ANATOMY - "All You Need Is Love" - In the spirit of Valentine's Day, Meredith and Derek try to have a night to themselves when Lexie offers to watch Zola; Callie hands babysitting duties over to Mark so that she can surprise Arizona with a romantic evening; and Ben proves to Bailey that he knows her better than she thinks. Meanwhile, the ER fills with romantics, including a 10-year-old girl who has an allergic reaction to chocolates from her valentine and a man who is hit by a car while chasing down his frustrated girlfriend, on "Grey's Anatomy," THURSDAY, FEBRUARY 9 (9:00-10:02 p.m., ET) on the ABC Television Network. (ABC/RICHARD CARTWRIGHT) PATRICK DEMPSEY, ELLEN POMPEO