There's a couple of verses in the New Testament that were mis-translated to help firmly establish monogamy only:
1 Corinthians 7:2
The Holy Spirit through the Apostle Paul:
Massive difference. The human translation = monogamy only view. In contrast to the Holy Spirit, which supports the man adding additional wives.
Next we go to the Gospel:
Matthew 5:28
The Holy Spirit through the Apostle Matthew:
That's a day and night difference between woman and wife. Almost all translations use woman, and the only Bible that I've noticed that correctly uses "wife” is William Tyndale's "New Matthew Bible,” which came before the KJV. He died as a martyr for Christ. The translation that uses "woman" makes it seem sex is a necessary evil. So logically more wives = more evil. It also makes it seem all lust is sin, but it’s how lust is used. The prescription from God for lust is marriage (those that burn with lust should get married). But if a man uses lust to fornicate with prostitutes, adultery, or break wedlock then it becomes sin.
Below is the New Matthew Bible from Mr. Tyndale's translation:
Matthew 5:28
On 1 Corinthians 7:2 I think that translating it as “own” in both cases is accurate although a bit unclear. However, with Matthew 5:28 I believe you are correct. I’ll have to dig a little deeper, but it appears that the specific word “γυναῖκα”, the Greek word used in Matthew 5:28, is translated as a married woman everywhere else it’s used, unlike the word “γυνή” which is elsewhere translated as woman.