She's prepared to hit him over the head, even though she knows it might kill him -- she might not, at this stage, have been devastated to have learnt that he had died 'off-stage', as it were -- but it simply isn't in her to watch a man dying in slow-motion in front of her and not lift a finger to save him. I'm not sure many people would be cold-blooded enough just to stand there and watch (Erik would!)