“And I say to you, whoever divorces his wife, except for sexual immorality, and marries another, commits
adultery; and whoever marries her who is divorced commits adultery.”
Jesus is saying that if a man’s wife commits sexual immorality, which includes adultery, he would be free to divorce her and marry another woman. However, if no sexual immorality has been committed, Jesus does not permit divorce. So, in answer to your first question, Jesus does permit divorce for adultery.
In answer to your second question, Jesus does say that divorce can be caused by adultery. However, there are other causes for divorce, though only sexual morality is permitted by Scripture. Other reasons people may give for divorce would not be approved by the Scriptures and thus result in sin.
This has been a brief answer to your questions. If you have other questions about this matter, or other matters, please feel free to contact us.
Christians are to be a forgiving people. In fact, unless they are forgiving they wont be forgiven by a forgiving God. Jesus makes that clear in Mt. 6:14-15,
For if you forgive men their trespasses, your heavenly Father will also forgive you. But if you do not forgive men
their trespasses, neither will your Father forgive your trespasses.
Jesus further tells Peter in Mt. 18:21-22 that we should be willing to forgive our brother who sins against us up to 70 times 7. However, we get more clarification regarding this issue in Luke 17:3-4,
Take heed to yourselves. If your brother sins against you, rebuke him; and if he repents, forgive him. And if he sins
against you seven times in a day, and seven times a day returns to you, saying, I repent, you shall forgive him.
Forgiveness comes after one repents. To repent means to change ones actions. Jesus makes that it clear for God to forgive one for his sins he must repent. In Luke 13:3 we read,
I tell you, no; but unless you repent you will all likewise perish.
So, one can get forgiveness for adultery. He must repent thus changing his actions. He must stop engaging in adultery. Then he will be forgiven if he asks God for forgiveness.
However, none of that changes the fact that Jesus teaches in Mt. 19:9, and other places, that the only reason for divorcing ones wife and remarrying is sexual immorality. One who divorces his wife for other reasons can get forgiveness, but he does not have the right to marry again. One can get forgiveness for robbing banks if he repents and stops robbing banks. He cant keep robbing banks and get forgiveness.
Regarding Hosea 3:1-3, we must understand that Hosea lived under the law of Moses, but we live under the law of Christ. The law is now different.