I think Littletimmy's answer is pretty much what I had in mind. To explain a bit more, there can be situation where sex happens but one of the party could not r

I think Littletimmy's answer is pretty much what I had in mind. To explain a bit more, there can be situation where sex happens but one of the party could not refuse for various reasons, and the other party have deniability of coercing. For instance, a boss asking an employee for sex after a diner, and the employee feels coerced but doesn't say anything. Effectively it would be rape, the boss should not be considered innocent of profiting from a position of power, but it can be argued that the employee could have legitimely wanted to have sex judging from his/her attitude. For me that's grey in the sense that while from the employee's point of view it's rape, from a third party point of view it's hard to factually prove so. To be clear, I don't use 'grey' in the sense that it should not be punishable or anything, it's not a value judgement, just that from a legal point of view it's trickier than violent rape.