Is it permissible to have intercourse with one's wife after the cessation of menstrual bleeding but before she performs ghusl (ritual bath), and what are the consequences if that is impermissible?

A wife does not become permissible for her husband after menstruation until the bleeding stops and she performs ghusl (ritual bath) thereafter. Allah Almighty says: "And do not approach them until they purify themselves. But when they have purified themselves, then approach them from where Allah has ordained for you." (Quran 2:222). If someone has intercourse with his wife before she performs ghusl, he must repent if he was aware [of the prohibition] and not forgetful or coerced. However, there is nothing upon him if he was ignorant or forgetful.