It's complicated. Men make it complicated unnecessarily.

Dollars to donuts, if she's into it, it's obvious. She's consenting and participating all along either verbally, physically (she's doing things to you too rather than "just laying there"), there's no sort of withdrawal, etc.

If you're confused or unclear, what in the world is stopling you from checking in? You do that with everything else in life. You follow up and ask questions when you're uncertain.

If you're not sure if you have consent, you don't have it or you lost it until you're clear you have consent again.

All that is obvious when you not just engaging in sex for yourself, selfishly. When you care if the other person is enjoying themselves, you'll look to see if they are, naturally.