性行为里的知情同意为何如此困难？

就这个问题我和我一个美国男性朋友讨论过，具体如下：

我：If on a date, a woman wants to terminate the intimacy half way, is that OK?

Ta: Sure. A girl can choose stop whenever she wants.

我：but if the guy does not want to stop and choose to force himself on her? What can she do? How to prove she was forced?

Ta: no need proof. When a girl claims she was raped, it is the guy’s responsibility to prove the sex is consensual. And she should call the police immediately after the rape. Because maybe some evidences such as bruises or skin torn can be collected.

谈完之后我意识到如果女孩子被欺负，一定要立即报警。不过他也承认这个社会充斥着男性沙文主义，很多男人觉得理所当然，特别是女孩子邀请他们去家里的时候。另外社会意识的建立真的不是一朝一夕的，需要长时间和金钱的投入。在这个问题上社会体制太重要了，譬如保护女性的体制、以及法律和医疗协助体制甚至创伤恢复体制。很多男人经常为自己找借口，说因为一时性冲动或者说女人引诱？既然杀人防火都是因为冲动、欲望以及金钱引诱，杀人犯纵火犯都要送进监狱，大众都是压倒性的支持，难道抢劫犯不应该同样被惩罚么？难道身体上和精神上的伤害就低于金钱和财产的毁灭么？

最后希望大家做人不缺爱，做爱不缺人！