The problem with this hand is your turn bet has too soft. The chances of him flopping a set or two pair are minimal and with straight and flush draws, certainly he'd raise considering that he's the chip leader. Your turn bet shoulda been between 2,000-3,000 to make him feel a little pressure. Betting 1,000 into a 3,400 pot gives him 3:4 to 1 to call and thus justifies why he did. Say the opponent has AK, AJ or K? diamonds, the odds are good for them to call on a gutshot straight, double gutshot staight draw or outdraw you with a better flush. Passive play cost you this pot. Next time in this situation, reevalaute what hands and beat you and the chances your opponent is holding one of them.