How many wives were allowed greek mythology?

Greek mythology is the lore of the ancient people of Greece; there were separate city-states and kingdoms that had differing lore, this is why "Zeus" had so many affairs, because the wife of the local god became the lover/wife of "Zeus" in later myths.

Zeus and Poseidon are known to have many 'wives' or 'brides' according to mythology for that reason; most were later regarded as affairs between the god and goddess/mortal.