Of course it is impossible

And I must say, it was Ethan who convinced me of it.

Consent assumes perfect communication between two or more agents. If I ask, I must be certain that her claim to consent is not mediated by any other kind of external incentives, social structures, insecurities and second thoughts. At the same time, she must be certain that my asking is also sincere and not itself mediated by other incentives, social structures, insecurities and second thoughts. Since neither of us can be sure of each of our halves; consent is impossible.

It may become possible one day when we can plug into each other via computer ports and have direct dialogues between minds. But it isn't as of today.

With newly found humility in the capacities of mankind, the only applicable standard is that which we apply with those we always realize we cannot perfectly communicate with, ie animals: obvious harm.

Anything further is factually impossible and usually logically inconsistent.