Eren would probably feel the same in Reiner's place, glad to cause hurt if he'd been hurt. But even though this is entirely his fault, he's sore about it. He's a hypocrite with a shitty temper, after all.

Eren isn't really expecting the help. He sure doesn't deserve it after that stunt, playing Reiner's confusion against him. But Reiner is still nicer than Eren, and even being pissed he still helps Eren out of the water. Eren accepts, then sits there on the edge of the beam, legs in the water. He lets his own anger (mostly) drain away, dripping off him like the water from his hair.

"No," he answers, almost sullen. He follows what the question is really asking. It's not about the game. Of course he's not satisfied about that either, but he's lost his taste for getting his ass kicked at this.

He stares down into the water for a minute, coughs again. Ugh, saltwater really is disgusting.

He chews on his lip for a minute.

"I shouldn't have done that," he says. It's not quite an apology. He's not prone to giving apologies to people. They don’t really matter to him. Once the damage is done, what good are apologies? He's too used to his actions being unforgivable.