Don't think there's a mistake here, there's two ways to get to Jade's pool sex scene, depending on how many Rebecca points you have?
You need 7 nJadeLove points if you have 3 or more nRebLove points.
You only need 3 nJadeLove points if you have less than 3 nRebLove points.
I've played through this scene with both scenarios to confirm.
So basically Jade has to be really into MC to proceed if he disappointed Rebecca by not accepting her swimming lesson.
If you're not flirting with Rebecca much, then there's a lower bar to get Jade's pool sex scene.
Since there's some confusion here, I'll reformat it to try and show the >= 7 bit only applies within the Rebecca block:
Thanks for the feedback, it's useful to highlight areas which aren't clear enough.