Abusers will not only insist they didn't now when they hurt you, they'll actively resist any information that would lead them into finding out.
You give any sign of pain they're attacking you from 10 different angles, blaming everything in sight (mostly you) and then when you tell them directly that they hurt you, they're suddenly allergic to information lalala I couldn't have known, why didn't you say anything. But you did and it's still 'I'm innocent I knew nothing I still don't know and next time I do it I will still not know what I'm doing, no information gained here. You also hurt me that one time and I'm about to attack you for that right now to distract you'.
And when this happens they either expect us to fold under pressure and give them a suspension of disbelief and make ourselves believe that they're just to unbelievably stupid, or they're insulting our intelligence, laughing at us because they think we're stupid. They know exactly what they did, and it if happened to them, there would be no end to the hell they'd raise about it.