Tina has to beg- repeatedly.

"I will only say this once. From now on, if you want to cum, you will ask permission. Understood?"
The man keeps fucking her.

When she doesn't speak up immediately, he spanks her ass once.

"Yes! I understand!"
"We'll see."

A minute or so later, she feels it coming.
She knows what she has to do.

'Think of the pins. Think of the clamps.'

"May I please cum," she asks.
"You can only cum when I count down from 10. 10...9...8..."

Tina uses all of her energy to hold the orgasm back.

When he reaches 1, she cries out in ecstasy.

'I've never cum as hard as I have these last few days!'

The man keeps fucking her.
He doesn't let go of her hair.

A couple of minutes later, another request.

"May I please cum?"
"10...9...8...7..."

He keeps counting slowly.
She cums at 1.

He eventually stops pulling her by the hair, but doesn't let up otherwise.

She tries to hold out.
Every request to cum is a moral loss.

She tries.
She can't do it.

Another request.
Another countdown.
Another orgasm.

Another defeat.