He survived the bloodbath, mostly due to the fact he used the Six girl as a shield against the Two boy. He didn't like it, but he knew he had to if he was going to win the Games.
Plus, the fact that he'd overhead the girl call him a "weird fucking loser" during training helped him justify it, even a little, in his mind.
His district partner was easier to justify. She had treated him like he was diseased, so he had no qualms about kicking her to the ground and leaving her for someone else to finish off.