JULIA Stiles and her beau of more than two years, artist Jonathan Kramer, have split over "irreconcilable differences." The breakup may have left the actress in a foul mood; a spy says Stiles got worked up the other day at Café Frida, on Columbus Avenue, when some nearby diners started taking snapshots of themselves. Stiles assumed they were snapping her, and as they left, she waved to them and said, "Bye, guys - glad you got your picture!" A rep for Stiles said, "Julia was trying to get out of the way of the picture. She wasn't being sarcastic."