From the creation of man , it was God's plan for a man to marry one wife and from the bible that Eve's ribs was gotten from Adams ribs which implies that God is after one man and one woman.
Now , with most traditions or religion practice by most people, which approved Polgamy I will say that's an error because it as against God's creation. I wonder why a man will marry morethan one wife leading to fighting, malice and sometimes leading to death. This comes as result of selfishness, lust or even self gain.
Therefore before a man or a woman think of marrying morethan one man or one woman think of wether Gid will be happy with such fellow ans as rasumtof some don't read the bible as such they don't follow God's instructions and leading. I will encourage that we should obey God's word as it is written concerning one man and one woman.