This is an important topic that is poorly understood and which contributes to rape culture. While a man’s erection or a woman’s lubrication are sometimes cited as signs that they “wanted” sex, so therefore could not have been raped or abused against their will, this simply isn’t true. Genitalia often respond autonomously, when their owners have no interest in having sex. Or don’t respond when they do. Arousal non-concordance is a physical fact that more people need to understand, particularly victims of sexual assault who felt shame by how their bodies responded during a non-consensual event.
I remember reading about a study done in Canada when they showed men and women pictures and measured their "response." Women got wet watching gorillas copulate. Scientists didn't know what to conclude. They definitely did not want to f*ck those gorillas. What they decided is that lubrication happens to protect the woman's body during a possible assault. It doesn't mean she wants to be assaulted. It means she hopes her vagina won't rip. Or her nervous system does...