Peleus didn't outwardly show hurt or pain, he was built a warrior like his son, but there was a sense of uneasiness that maybe he had failed his son a long time ago. "He does deserve that." Only Thetis might be able to tell that he wasn't satisfied with things as they were. "Maybe it will bring him some peace." But it did not bring him any. That wasn't how he expected to live this life with his son at a distance.
The water hit his feet, trying to soothe that pain.