Okey , he should kill her
Spoilers here of course! (⊙…⊙ )
Just to clarify… The girl's not in her right mind, even before being pulled into this death game. She's been bullied for a long time, and she's just been murdered by her bitch classmates. She's already got her mind locked in the mindset that no one's going to help her, so she probably can't comprehend that the MC is actually trying to save her life. That's why they also included the whole part of her backstory with the PE teacher telling their class not to try to save a drowning person, because in their state of panic they will literally "grasp at straws." And, she also literally drowned as well!
If you have ever read the novel Dune by Frank Herbert, there's a part where that MC describes another example where a drowning person will even climb on top of another person to save themselves - which is pretty much exactly what happened with this girl. Not that I don't completely agree that she should have at least jumped on the corpse of the guy that she already killed (also accidentally - she is not a murderer!) - but the whole point I'm trying to make is that she is in no way sane at this juncture, nor is she thinking clearly, and I just plain feel sorry for her.
If u r sorry then jump to the corpse, not him