An unkept promise is a well disguised orgasm

I had transgressed.
The rules were clear: no penetration.
She was lying naked on the bed; her position was that of the "Man of Leonardo".
I knelt between her spread thighs and my hands leaned near her hips. My chest was on her belly. Slowly I climbed touching her breasts and I arrived with my mouth on her lips.
First transgression: my tongue moved her lips away and forced white teeth. In the damp of her mouth my tongue intertwined with her one.
I never imagined it would happen: my cock, hard and pulsating, without any guidance, opened the road between the labia of her vagina. I was penetrating her; my desire had won on the promise that we made there.
In a final attempt to respect the rules of our game, I did not continue the movement. She, with my cock planted inside, began to contract the walls of her cunt. It did not take long for me to come flooding her and not keeping our promise.