He might be a klutz, but he sure knows how to sweet-talk to his gf.
@anon_whos_not_a_fag - "higher carbon"? Where's that "carbon" coming from? And where is it going to? No, you got it right with the arteries - light red arterial blood is high in oxygen, so dark blood travelling back to the heart/lungs is low in oxygen. But the problem with a burst major artery is primarily loss of blood, and subsequent collapse of the circulatory system/shock.
@Svelandria - Good observation (I had also missed it). But I think this does not mean that she's bad at first aid, on the contrary, it means that she's a god-like being who can apply a bandage to one limb in order to stop the bleeding on another. Pure magic!