It's more than none - she struggles until her hands leave (the body, Guenievre is gone), doubles forward momentarily in an effort not to be drawn too far and it's not a decision to stop so much as she loses her balance and the decision is taken entirely out of her hands.

The sound she makes isn't despairing, isn't the sort of ladylike and pretty distress that even she's capable of turning to great effect; it comes from the bottom of her stomach and it's wounded -

"I promised," she says, savagely angry, clutching Lex's arm with bloody hands. "We were nearly there--"