If a female student goes to her college professor and says I'll sleep with you if you give me good grades that's willful consent.
If a college professor goes to his female student and says if you don't sleep with me I'm going to fail you that's not willful consent.
Rape is non-consensual sex. There's more than one path to get to that destination.
Your argument that consent is going along with someone in a situation where there is a power imbalance under threat of being crushed by that power imbalance is laughable. Consent means you wanted it of your own free will and of your own accord. Consent doesn't mean you acquiesced to a threat because the alternative was a very bad situation for you.
Sexual assault can include physical touching rape is non-consensual penetration.
She could go to HR is comical. It's her word against his and he's more powerful and important than her. There's a reason many women who get raped or sexually assaulted don't say anything. That reason is retaliation. Go to HR and the person that did it will be tipped off and if you can't get them fired they're gonna retaliate. Depending on the state you work in and at-will employment you can be fired for anything but they'll probably invent a BS reason to do it.
:plasticreach: