Thankfully, we don't abide by the world's culture, but by God's culture. In the New Testament it says one wife. When God made man and said that man should be alone, God didn't create multiple women for him (wives), but one woman (wife), Eve. I think by that statement alone we know what God prefers. Adam didn't have multiple wives, did he? Nope. It was only when the chosen people became influenced by the world's culture that they took multiple wives.
Plus, out of all the histories in the Bible, we only have a handful that had many wives. We must remember that these men were human and made choices based on their flesh, just like we do, and we shouldn't assume that because they had many wives, God was okay with it. I don't believe the Bible ever says "God is okay with many wives" or polygamy would be legal, right?
Quote taken from: Here's the Plain Truth About OLD TESTAMENT POLYGAMY
Not really. It never says anything about having only one wife. It says that you should love your wife. but this language doesn't cancel out loving your wife Teresa, while loving your wife Sandra, while loving your wife Beth. Not everyone had multiple wives. It was mostly the more wealthy that could rack up multiple wives (imagine having to support these women and their offspring). If the NT said "love your wives" then that would imply that men HAD to have more than one wife, which they didn't and often chose not to.
The only thing that changes in the Bible in terms of the acceptability of Polygamy is the culture of the Geographic region. Remember that the OT and NT are (mostly) books from different parts of the world.