"Maybe that's another stage..." she says in a distracted way as she fingers herself furiously. "When you are begging to stop, that must mean you are really close!"
Yes, you agree hoarsely. You beg her again to please let you stop! You can barely stand the sensations your hands are giving your cock, and when you look at how turned on she is, you feel that you are that much closer to cumming! You feel the sperm moving up your cock as you drip pre-cum on the carpet.