Is the penis relaxing upon penetration, and attempting to stimulate it by hand or by rubbing it against the thigh in order to ejaculate and enjoy with one's wife, considered forbidden and akin to masturbation?

What is done by the wife's hand or at any place on her body is permissible. However, what is done using the husband's hand or thigh is considered masturbation, or could be a gateway to it, therefore it should be avoided. Merely touching the penis without intending to arouse desire is permissible.