Numbers 5:12 - Joseph Benson’s Commentary on the Old and New Testaments

If a man's wife go aside From the way of piety and virtue, and that either in truth or in her husband's opinion. This law was given partly to deter wives from adulterous practices, and partly to secure them against the rage of their hard-hearted husbands, who otherwise might, upon mere suspicion, have effected their destruction, or at least put them away. There was not the like fear of inconveniences to husbands from the jealousy of their wives, who had not that authority and power, and opportunity for the putting away or killing their husbands, which the husbands had with respect to their wives.