I am usually the first to fold in almost any situation. But is he really never bluffing here? You raised pre-flop, so you're cbetting. He sees the flop is raggy and monotone - if you haven't hit moderately well here, you're in a very tight spot, and if he's any good he should be able to take the pot with air. If he has a pair or a draw, he can optimistically feel that he's in a strong position.