Japan is weird...
...AND OF COURSE THE BLONDE WAS TOTALLY CLUELESS OF THE WOMAN'S FALL, EVEN THOUGH SHE WAS THE NEAREST.
That's what she gets for dancing in heels on a wet stage, and for trying to mimic American w*res instead of doing her own thing.
Notice how the other members keeps dancing?
During their training, their company tries to program them with all of the ways they're supposed to react to various situations, and, when something goes wrong like this, their pathetic little brains get overloaded trying to process all of the memorized reactions in an effort to figure out which reaction is correct.