Marriage covenants were unilateral because of the bride price. It said, a man "acquired" his wife under the law (Deuteronomy 24:1) as Abraham acquired land (Genesis 23:13). No one could terminate a marriage covenant before Moses' permission. Jesus said, divorce was not an option at creation (Matthew 19:8 "from the beginning [divorce] was not so."). Covenants were for life ("till death due us part") because of the blood. Wine was called the blood of the grape and tearing of the virgin's hyman in consummation represented a natural blood covenant. But Moses mediated for the people and eventually allowed man to divorce his wife for sexual immorality in a unilateral covenant, under the law, because of the hardness of his heart. Christian's apply Moses' unilateral permission to the man and the woman because we practice bilateral (not unilateral) marriage. But nowhere in the New Testament does it say women can take advantage of Moses unilateral permission he gave to the man in the Old Testament. It's just assumed because we don't understand the differences being Gentiles (no longer practicing bride prices as seen in the Old Testament). Monogamous societies had men and women come together as equals in marriage. Gentiles likely practiced dowry (money given to the groom from the brides family) at the time. Gentile believers were not accustomed to patriarchal societies where a woman was acquired by the man with a bride (purchase) price, allowing polygamy. The Nations surrounding Israel (Rome and Ancient Greece) were strictly monogamous at the time of Jesus. Greece for many years before Rome. And this is where most of the confusion of divorce and remarriage in the Bible comes from.