What is the ruling on semen discharge from a man after foreplaying with his wife over clothes through mere friction, knowing that this occurs even when he is dressed?

The emission of semen when a husband caresses his wife, regardless of the nature of the caress, necessitates ghusl (ritual bath). The ruling is not affected by whether the semen was emitted while wearing clothes or through skin-to-skin contact. It is possible that what is emitted during caressing is madhy (pre-seminal fluid), which does not necessitate ghusl but is impure.