Maybe this is similar to when he had an orgasm via ass back when rui showed him how to get off without cumming with his dick...and even if he does cum, wouldn’t it take a while before he changes to a woman? after they had gay sex shion took longer to turn into a woman than all the other times.
I can already foresee it,,,, He going to cum and his body is going to morph to it's 'female' form