Throughout history it has been difficult for a single woman to live independently. This has been true especially when she has had to provide for her children. She has found it to be expedient, if not necessary, to marry so as to have a husband to provide for her.
When a husband was displeased with his wife and caused a separation without giving her a divorce, it was a special form of cruelty, for she would not be free to marry another man. Because of the hardheartedness of her husband, she would be driven into an impoverished and outcast state.
Pharisees tested Jesus with questions about marriage and divorce (Matt. 19:3-9). Jesus assured them that God intended that marriage ties would be permanent; yet Moses had commanded that a certificate of divorce be given by the man who put his wife away. The reason: "For your hardness of heart Moses allowed you to divorce your wives, but from the beginning it was not so."
Because it was unmerciful to send a wife away to be denied the support of a husband, Moses has said, "Divorce her!" Being divorced, she would be free to remarry. This merciful course alleviated the hardheartedness and pain of being rejected and driven out.
If Jesus had not granted the same protection for the rejected wife, he would have been giving approval of the callous heart of the husband.
When we contend that the divorced wife cannot remarry, we are laying the same cruel burden on the woman.
When we declare that her only appropriate course of action is to remain single or return to her husband, we fail to recognize that Moses would not permit her to return to her first husband after being divorced and remarried (Deut. 24:10. Divorcing her second husband and returning to the first one was not an acceptable solution.
Paul grants to all the unmarried women (which includes maidens, widows, and divorced persons) the privilege of marriage. The woman who left her husband to be more devoted to Christ must either remain under that celibate vow or return to her husband (1 Cot. 6:1-12). He did not impose a cruel single life on anyone.
So, divorce her instead of just separating, and let her remarry.