Stacy

Your girlfriend Stacy has been slowly conditioning you over time to implant a trigger for your orgasms that's associated only with her voice and her command. It started with her building it up during sex. She would guide you to cum when she wanted you to. You and your body learned to understand the conditioning. You wanted to please her and would do your best to cum on her command and your body had trouble cumming without it.

Now, she has deepened her conditioning of your orgasms to push it further to make you cum on command whether you want to or not, even without needing stimulation.