[pdiggz]

I think this depends a lot upon his preflop 3bet range. Also, if he has an Ace is he usually betting it on the flop, especially with 2 hearts on board? Would he play the hand like this with 88,99,TT,JJ? You have played flop/turn pretty weakly, so your hand is under represented some. He could just be picking up on this and betting the turn, with a lot of hands.

If his range is made up of mostly KK, AA & Ax, and rarely folds any of these hands, when raised, then folding is fine. If you would fold out a lot of his range by shoving, then that would be a good play, also. But at NL25, he is probably calling a shove with KK and Ax.