1 Jesus then left that place and went into the region of Judea and across the Jordan. Again crowds of people came to him, and as was his custom, he taught them. 2 Some Pharisees came and tested him by asking, “Is it lawful for a man to divorce his wife?” 3 “What did Moses command you?” he replied. 4 They said, “Moses permitted a man to write a certificate of divorce and send her away.” 5 “It was because your hearts were hard that Moses wrote you this law,” Jesus replied. 6 “But at the beginning of creation God ‘made them male and female.’ 7 ‘For this reason a man will leave his father and mother and be united to his wife, 8 and the two will become one flesh.’ So they are no longer two, but one flesh. 9 Therefore what God has joined together, let no one separate.” 10 When they were in the house again, the disciples asked Jesus about this. 11 He answered,“Anyone who divorces his wife and marries another woman commits adultery against her.12 And if she divorces her husband and marries another man, she commits adultery” (Mark 10:1-12; cf. Matt 19; Luke 16; 1 Cor 7).
For the sake of argument, let's say that Jesus taught something quite similar to this. What's the point? What is Jesus getting at? It's not like the Pharisees were anti-family. If anything, Jesus' other sayings about family lean in this direction (e.g. Mark 10:29-30).
Is the motive to ramp up Scripture's teaching on divorce, or was the aim to undermine Moses' authority (thus the appeal to Genesis rather than a legal text)? What was the Sitz im Leben Jesu? Or, put another way, what made this particular (seemingly unique) teaching meaningful within Jesus' movement?