On the day of the wedding and whilst waiting for Cinderella to appear by his side at the alter, one of the ugly sisters begins to flirt heavily with the Prince and starts to get him feeling randy despite his pending wedding and so he thinks 'sod this - I like being a playboy' and so bunks off with her for a quicky in the vestry.
Cinderella arrives to find no Prince Charming, no sister and a whispering guest packed church. Immediately she knows something's up. One of Prince Charming's friends who secretly admires Cinderella and really wants him for himself, decides to put the boot in for Prince Charming by telling her the truth, (with embellishments of course) and tells her also about the bet in the first place.
The friend then goes on to tells her where her soon to be husband is so she can catch him at it and she walks off to see for herself if the friend is telling the truth.
The friend figured that once Cinderella saw Prince Charming doing the bump and grind moves, she would get hysterical and upset and would need a shoulder for comfort and he planned to be that shoulder by making sure he was in the right place at the right time so that he would be the first person she would turn to for comfort and at which point he planned to take full advantage of her vulnerable upset state by sleeping with her himself.
So the friend shortly follows Cinderella to the room and waits outside patiently knowing full well that she is just about to run out of it and hopefully into his arms. However, as he stands there with open arms ready to receive Cinderella - fully prepared to act with sympathy and provide words of concern, she walks slowly and calmly out of the room towards him, asks him to stand aside and as she comes level with him, she momentarily stops and whispers into his ear - not sure what, but he goes white as the blood drains from his face and he is left shocked and frozen to the spot with his arms still outstretched as she continues on her way gracefully.
With head held high Cinderella appears to float serenely down the aisle in front of all the now stunned guests as they can't believe how calmly she's handling the situation - they were looking forward to the emotional fallout and shouting and crying and major wobblies being thrown everywhere but she gives them nothing. In fact, they are spooked by how quietly, composed and serenely she continues to walk down the aisle through them and out of the church to disappear into the twilight evening -
Fienderella is born!