"Don't touch me!" kills the mood expediently well for me no matter how long I've known a woman, and no matter what our 'relationship status' is.
I can't relate to the necessity of a line that apparently needs to be drawn here.
How can there possibly 'degrees of allowed resistance' in sex?

I can dig it... But I can NOT relate.
There cannot be "degrees of allowed resistance". Either she wants to have sex or it is rape.
Sure there can. Plenty of wives aren't in the mood, say so, their husbands gently persist, the wife gets in the mood and they both have a fantastic time and no, this isn't always wives doing their wifely duty, they actually had a very good time having sex. So this standard of yours isn't as rock solid as you imagine it.
I do though think your standard should be applied in a brutally honest fashion for singles. As the first utterance of "no" the man should stop, pick up his jacket and walk out. He is there for sex, she says no, he's being honest and leaving. Couples don't magically get to the point where sex becomes an issue, they're not dropped there from a cold start. There have been signals passing back and forth all evening, escalating the intimacy. At each step of the way the women knows that they've both moved one step closer. Why is she bothering if she knows that she won't have sex? None of this is meant to excuse men who rape a woman when she says no, it's meant to highlight that women often need a bit of coaxing as the couple approach the end zone. Woman are now saying that "No means NO, always and without ambiguity." OK, men should listen and also give a message back, without ambiguity - "I'm taking you at your word" and go cold. She led him on, he's unhappy with being lied to.
This is a nebulous zone - some women want a little more persuasion before they say yes, so they say "no" and mean "keep trying" while other women say "no" and actually mean "no." The ones who say "no" and mean "no" are not the problem, it's the ones who say "no" but really mean "persuade me some more" that are the problem
.
The way to reform the "no means try harder" women is to cut your loses and leave. Actually, don't even say a word. Leave her wondering. She'll figure it out. It's these women who are ambiguous who are causing the problem because they're undermining the message from the other straight shooter women and there's no way for a guy to know which kind of woman he's dealing with. When he guesses right, he has consensual sex, when he guesses wrong he's a rapist.