Sometimes I wonder how people here interact with another person... Human interaction is all about reading signs and acting upon them. This obviously leads to things sometimes being misinterpreted which is unfortunate. Pretty damn sure most if not all who have engaged in sexual activity have done so without explicitly saying you both want to engage in it.
I think a big part of these events in which girls and women express they are afraid of saying no is due to we as a society tends to scare them all the way from when they are kids. I mean, if they are scared to say no even if you ask "do you want me to do this?" they would probably say yes since they are scared to say no so not even asking for consent would help in that situation.
I don't really know how to fix it beyond being clear from when they are kids, both girls and guys, that you should be clear when you say no. That even helps investigation to make a proper call. If they still assault you even if you say a clear no, then yeah nothing you could do except fighting back, but if you don't say no why would anyone stop?
Empower people, don't scare them from a young age.