The separation.
The Pharisees asked him to tempt him, if it was lawful for the husband to repudiate his wife "
Source
The Pharisees appeared again on the scene with the same intentions as always: seek how to catch the Lord in their words in order to create problems.
The question that was raised on this occasion touched one of the most discussed points in the rabbinical schools of those days. So, whatever his position, he would immediately be opposed by a good sector of Judaism.
But it was not only a matter of choosing between two rival schools on the subject of divorce (that of Hillel or Shammai), but also the case of Herod was still in the air. We all remember that John the Baptist had strongly denounced King Herod because of Herodias, wife of his brother Philip, from whom he had divorced to marry Herod. John the Baptist reproached him for it: "It is not lawful for you to have your brother's wife." And as we know, this cost him his life (Mr 6: 16-18). Would Jesus speak with the same boldness that John had done? The Pharisees knew that it would be so, and they expected this to lead to the end of their life without them having to "stain their hands."
All this spoke very badly about the Pharisees. On the one hand there was their hatred and hostility towards Jesus, but on the other, the triviality with which they dealt with such an important issue as marriage and divorce, manifested a hard and insensitive heart.
For them, marriage was not a definitive link. His own question revealed that they thought of him as something temporary. And on the other hand, they couldn't hide their machismo either: "Is it permissible for the husband to repudiate his wife?" For them the woman had no legal rights, all were available to the husband.
Credits for luis de miguel from the biblical school.