The “it will ruin sex” objection is one of several common objections that I think are rhetorical and fall apart under even casual scrutiny. For example:
“Why does the guy have to secure consent?”
He doesn’t. It’s a gender-neutral obligation. Initiator secures consent. Worked fine at Antioch.
“What if they are both drunk?”
“What if nobody initiates?”
Not possible. If two people lay in bed next to each other, no sexual contact takes place. If we mush up “sex” into some gauzy montage, and refuse to consider it as anything but a unified whole, it becomes possible to have a confused situation about initiation. But each act has to have an initiator. It is that person who has the obligation in the first instance.
“What if they initiate mutually?”
Well, that’s enthusiastic participation. If two people lean in to kiss each other at the same time and stick their tongues in each other’s mouths, I think we can be pretty clear on consent.
“But … Isn’t It Awkward?”
Well, here’s the beauty of it. It isn’t, because people can always bargain around the law in private arrangements, and law provides a background rule. The person initiating has the obligation to secure consent. In the presence of enthusiastic participation, that person may be so clear on the existence of consent that they don’t need a verbal confirmation — but they have to be willing to assume the risk of error. The non-initiator, if they are for example a survivor who freezes, faces serious consequences from a mistake, and the initiator faces serious consequences from a mistake theoretically (but not actually because there are no convictions in these situations). But the initiator is more able to avoid the mistake by checking for affirmative consent. As I recall, “stop if your partner goes limp” was a rule of Fight Club. If a bunch of guys fighting in a basement can observe that, we can expect it between sex partners, I should think.
The other way to “bargain around the rule” is to explicitly agree that silence equals consent and set other conditions for revocation, which is what BDSMers do with safewords and safesigns. Empirically, the experiment worked at Antioch, where the students loved the policy.