If you’re talking about during sex, then yes. Either party has the right to withdraw consent at any time it’s ongoing. That’s not changing the rules. You stop, or what was consensual now becomes rape.

But you’ve been talking about long after the fact. And that’s where you’re off. It’s not changing the rules to seek clarity. That’s like… you’re playing monopoly but you don’t want the game to go on forever so you do away with mortgages. Then someone asks, "That includes utilities, right? We mean all mortgages, right?" You’re not changing what you agreed to, you’re seeking clarity.

Maybe a more exacting example would be you’re playing monopoly and you want the game to last maybe 2 hrs. So you agree to no mortgages. You play the game and it goes 3.5 hours. The next day was rough for you because you have to be at work at 5am and the kids were an absolute nightmare because they were up past bedtime. A couple of days later you say, "That was still way too long for a weeknight. Maybe we should zone out some properties from sale and lessen the bank accounts we start with."

You’re not changing the rules on the game you already played, you’re seeking to make the next game not have any deleterious consequences you didn’t see beforehand.

In that light... yes, it’s entirely possible for someone, days after, have some negativity toward a sexual encounter that they didn’t expect. Wanting to clear the air because something, upon reflection, made you wary or uncomfortable is not the same as pressing rape charges down at the local precinct. And just because they’re upset about it doesn’t mean they blame you. Maybe they do and maybe it is on you, but it depends. You can’t make that assumption until you know exactly what the problem is and why.