In summary, let's keep rape as a reserved term for obvious and gratuitous violations. This "accidentally raped" is kind of stupid.
Men and women have unwanted sex all the time. They do it because they don't want to let their partner down, because they think it is their "job", because they want to get something, because they are bored, because they want to feel wanted, because they just want to feel loved, because they haven't in a long time, etc. -- not always the best reasons. Typically, those feelings can be resolved in other ways.
We, as lovers, should strive to reduce the number of unwanted sex events as possible, and to do so requires an open bidirectional communication channel. However, while it may be sad that women are more prone to agreeing to unwanted sex, this is not the same thing as //raping// someone. I think it's really important to make the difference, because for one we say that the relationship is a bit off, in the other, we lock a person up and mark them for life.
In the aftermath of the guilty verdict, several people observed that many of the teens at the party didn’t realize that this was rape. To them, the fact that the victim was unconscious didn’t mean anything. “I didn’t know this was rape,” said one witness. “It wasn’t violent.”
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In many ways, the focus on “no” puts the burden – yet again – on women to rein in the libidos of men who presumably can’t control themselves… and in many ways can put them at a disadvantage. Women are often socialized to be non-direct for fear of causing offense; many women are frequently uncomfortable with being up front with saying “No, I don’t want this.” http://www.doctornerdlove.com/2013/03/enthusiastic-consent/
This is much more complex than you make it out to be, and that's precisely what obliges us to set guidelines that encourage folks not to rape rather than assuming not-rape as the default.