I ruin her orgasm

A few seconds before the end of the five minutes I notice that she is close to orgasm, so I can't resist but twist her nipples. Taken aback from the surprise and the sudden pain my girlfriend loses her climax. The ring of the bell I set earlier notice the both of us that she has just lost the last chance she will ever have to reach an orgasm.

Immediately as it subsided she burst into tears. I cradled her head in my hands, saying "There there darling, I'm sure you tried your best, you'll certainly remember that forever. Unfortunately a rule is a rule and you lost your chance" However I was also trying to be genuinely comforting to her, as I did feel sorry. Nevertheless I reached to the bedside table and picked up the short cuff chain that linked her hands behind her back, and even as I caressed her I gently said "Hands behind your back baby." She sobbed, barely able to pull her hands away from her throbbing pussy, still wet because of her masturbation but I gently pulled them and she obeyed. I locked her hands tightly behind her back, ending her last sexual episode. She looked truly pitiful, so I kissed her and cuddled her and poured her a glass of water which I fed to her.