river fold? 8/16 live

[brick]

Two limpers. SB folds. I have 6sTs in the BB and get a free look.

Flop: 6c 4c Qd
I check EP bets, LP folds, I check raise. He calls.
EP reads hands well but plays too loose. He is probably a winner because he get more bets in when he is ahead than when he is behind.

Turn: Qh
I bet, he calls.

River: 5h
I check, he bets, I don't know why he would bluff here when he knows I'm going to call, so I fold.