Tell her that if she removes the collar, you'll use her pussy rather than her ass
From Create Your Own Story
"Take the collar off, and I'll be satisfied with some more of that tight pussy," you whisper in her ear. "If you'd rather not...I bet your ass is tighter."
"Please not there," she gasps. The prospect of being fucked in her ass seems to really scare her.
You let her up so that she can reach the key, but you don't let go of her wrist. She reaches out, almost grasps it, almost...then, as she grabs it, she tries to lunge away. Luckily, you were prepared for her treachery; your grip on her wrist closes a lot more tightly and you throw her, key and all, across your bed. You pin her down with your body as you take the key from her and unlock the collar from around your neck.
If you needed an excuse not to keep your side of the bargain, she certainly provided it to you.
