Consent really really is not a grey area, I don't understand all these confused people, we manage to ascertain consent in every other area of our lives! I think people do think it's something feminists have come up with to trick men but really is quite simple.
I remember once a thread (on FB not MN) about a woman who had given birth 2 weeks earlier and her OH was pestering her for sex. She'd had a 2nd degree tear and was still very sore down below so said no several times through the day. At bed time she was in her nightie and knickers and they were kissing passionately on the bed, she was touching his penis. All of a sudden he pulled her knickers down and penetrated her. She was too shocked or scared to say anything so just went with it, but was in agony afterwards, could barely walk. She asked the group if it was rape.
I'm sad to say the people like me who confirmed this was rape were in the minority. Many berated her for accusing him of such an awful crime, poor guy, lives are ruined by false accusations you know
. It baffled me that people couldn't see that saying 'no' several times in the day was the very opposite of consenting and that her vagina won't have magically healed come the night time! TBH it turns my stomach that a man is so selfish he thinks of his cock before he thinks of his GF's bruised and torn vagina which pushed his baby out just a number of days before.
I know these groups don't require an intelligence test before entering so you're bound to get a few thickos, but the thickos really went for her and it clearly affected her as she left the group 
I often think of that girl and hope she left him, she said he'd started to have sex with her in her sleep in a few times so was clearly a serial rapist.
The lines really aren't blurred, if she isn't consenting and enthusiastic about intercourse at the moment you feel like sticking your cock in her, it's probably because she doesn't want sex, and not pushing you off her doesn't mean she's going with it, it maybe means she's scared or been taught all her life that women are there to give men what they want and those who object are making a fuss over nothing. These incidents happen all the time. There's currently a thread about how mothers of boys are sick of hearing about how awful they are and sick of hearing about how they don't respect women, their boy is lovely so you know NAMALT. I wish these women would stop being precious for a second to look at men's behaviour as a class and perhaps educate their boys instead (even if they're not one of the 'bad boys') about consent and respecting women and how their penises are not above a woman's feelings and safety.
Something desperately needs to be done about our rape culture, and women (be it mothers, partners etc) to stop making excuses for shitty male behaviour would be a good place to start