Facing all-in on river with flush on paired board.

Blinds: 1/3/6.
Players 8.
Effective stacks 1120.

Pre flop.
Straddle is on.
UTG raises to 20, it folds to me on the button with KdQd, and I make the call. The straddle also calls.

Flop.
Jh 10d 7d

The straddle leads for 25, UTG raises to 150. I make the call. The straddle folds.

Turn.

Jd
UTG bets 300. I call.

River.

3s.

UTG goes all-in for 650.

Tough spot. I've played against this player quite a bit, and he usually has it when he bets big. I don't beat much. It feels kinda nitty to fold here, not really sure what to do.
Your thoughts would be appreciated.