Thanks for your question on Healthcare Magic. I can understand your concern. It is a known fact that cigarette smoking in general leads to impotency. Weed or marijuana smoking is highly associated with erectile dysfunction (lack of erection) and both of these in combination are too bad for sexual health in a male. Even otherwise, both these agents are highly addictive, and potentially dangerous as you must know. It is highly recommendable that he stops smoking both these agents as early as possible. He can seek medical attention for treatment of withdrawal. It is not easy, and you, as fiance, must persuade him and support him mentally to quit. Take care, Regards