Let's hope that res isn't banned for starting this thread in what someone thinks is the wrong forum.
God (Jesus) defined grounds for divorce, one of them being sexual immorality. If a parable about Israel's unfaithfulness to God (yet God continued to be faithful towards Israel) somehow trumps Matthew 19: 1-9, I guess I missed it.
No; he reminded THEM that THAT had been THEIR grounds for divorce due to THEIR hardness of heart - THEIR unwillingness to forgive in the grace that He forgave the woman CAUGHT in adultry.
There is no denying the bitter pill anyone in such a predicament would have to confront BUT this was a "weightier matters of the Law" issue.
Matt. 23:23 Woe unto you, scribes and Pharisees, hypocrites! for ye pay tithe of mint and anise and cummin, and have omitted the weightier matters of the law,
judgment, mercy, and faith: these ought ye to have done, and not to leave the other undone.
It is in that that the needed grace could be found - under the Law, no less!
As Paul noted "this same rule" (principle) under Grace:
1Cor. 11:31 For if we would judge ourselves, we should not be judged.
John 8:7 So when they continued asking him, he lifted up himself, and said unto them, He that is without sin among you, let him first cast a stone.