As for as Islamic Shariya concern one can have sexual relation with his spouse any time other than Holy month of Ramzan during day time or any time if anyone is fasting. Or a woman is not in the state
Hayz. But there is an issue related to ethics which says that you must follow some ethics also. Now being a shia how is it possible that one can enjoy the way he wishes while we are commiserating the martyrdom of Imam Husain a.s. Do anyone can have relation with his wife while he has just lost his father or mother and have not done their Chaliswan or 40th but I’ll say again this in not Haram to have sex with his wife in Moharram if his conscience allows him.
It is obvious that if anyone have sex then it is wajib to do Ghusl. Because without Ghusl you can’t do anything neither pray namaz nor touch the Quran.