This is an interesting question, because I'm not sure either. The obvious answer would be that many women have taken offense with the recorded conversation between him and Billy Bush; "revealing" his perception of women, which according to many should disqualify him from advancing further in the Presidential Election.
However, I've witnessed Donald Trump being disapproved (on- and off-camera) by (the same) women with the same zeal before that, even though their motivation changed throughout. Half of the time I'm uncertain whether they are attacking Donald Trump the person or the symbol. I mean he's not the first of his "kind"; the fact that many people relate to him, supports this finding. So are these protesters marching against him, or his (personal) views?