Its sad that most of the blank face sex is just a extremely short ending few seconds shots just to show the gal has given up. I wish they would do a more lengthy sex scene on blank face sex. But most unfortunate is once it goes normal sex scene , the training kicks in and they will start moaning in heat again.
I have come across recently a JAV by Sara Saijio
https://www.javlibrary.com/en/?v=javlikbgqy
She was something of a employed house helper , at a certain part , the bad employer just tied up her manager(I think) and proceed to do her.

After the employer done , the manager broke free.

The manager got a good view of a broken Saijo. And decided what every man must do in this situation.

It show the expressionless Saijo being humped by the manager without showing the manager and a very short scene. A very wasted potential