kuruman,
Your example is realistic and brings up a challenging question: Could it be at all plausible or "justifiable" to say that the "degree of resistance" defines whether rape occurred?
There are some very UNpleasant things about that idea...and also some practically realistic things about it.
Communication IS the key element, afterall. But then THAT can be unfairly miscontrued, as well: The "real" date rapist who claims that fairly active physical resistance was just "play wrestling" or something.
One has to be fair and say that there ARE scenarios in which women "relent" to rape because they feel that showing significant resistance could escalate the risk of dangerous confrontation (which, at the same time, that LACK of physcial resistance could have HONESTLY been interpreted by the male as agreement to the act).
For me personally, such things have NEVER been an issue in any way: I have NO INTEREST in sexual activity with anyone who isn't HOTLY interested in response. Apparently, it's not always like that for all other people at all other times (which is why these discussions sometimes confuse me).
....I'm just not sure that miscommunication is fairly construed as crime.