Let’s say you’re a woman, and you’ve been pulled over by a male cop. He’s got you dead to rights on possession of cocaine with intent to distribute after spotting the bales of cocaine in your back seat. He’s willing to just give you a ticket for a burned out tail light, but only if he can fuck you, right then and there. Can you, in that moment, morally and ethically consent to sex with him, when he has the legal authority to arrest you and ensure that your life is fucked forever if you do not consent? Most people would say no, that entire environment is coercive, so there’s no way that, within that framework I’ve presented, that the woman could morally or ethically consent to sex in order to make her ‘little problem’ go away.
2nd wave feminism presented all male-female relationships in that way, although usually with a less blatant abuse of power going on. If you assume that patriarchy stacks the power deck in favor of men, then there’s very little basis for women to ever consent to sex with a man, because she is never able to have an equal position of power within society from which to consent. But that’s also a problem, because it abstracts people to the point where it’s almost meaningless on an individual level.