The door nearby opens

That is, until the heavy fire door on the landing above swings open.

Cheryl steps through, lithe yoga-toned body framed in the doorway, and freezes. Her shocked face takes in the exact scene: Ruby braced against the concrete wall, trousers around her thighs, your cock buried to the hilt in her willing pussy, hips still moving.

The sight of her, the wide eyes, the parted lips, the sudden confrontation of the woman you dreamt of fucking over the conference table only hours earlier now staring at you balls-deep in someone else, is too much. Your orgasm hits instantly and hard. You unload deep inside Ruby in thick, pulsing waves, a low groan tearing out of you while you stay locked against her, unable to stop the climax even as Cheryl remains frozen in the doorway. You start to pull your cock out of her, cum dripping from your length and Ruby’s twat.

Ruby feels it and gasps, still pushing back, completely unaware for one more second of the audience until she follows your gaze and sees Cheryl standing there.