Jesus had set his sights for Jerusalem just before his death. He declared that he would encounter opposition, be arrested, be tried and executed, and rise on the third day. Huh? His disciples could not get his meaning, especially about the dying part.
On his way to the Passover showdown in Jerusalem, Jesus expressed his sorrow for the city (Luke 13:34f). He lamented the state of the city: O Jerusalem, Jerusalem, you who kill the prophets and stone those sent to you, how often I have longed to gather your children together, as a hen gathers her chicks under her wings, but you were not willing!
Jesus is frustrated that the people of Jerusalem were so blind and deceived. He is sad that his people would not listen to him, and that they did not recognize him. He offered them such hope and redemption, but they rejected him.
The religious establishment of Jerusalem had a long track record of missing the message of prophets. This day would be no different. The authorities rejected and even persecuted those who spoke truth. And even Jesus's closest disciples weren't tracking.
No wonder Jesus was sad. Their rejection would mean pain for Jesus and hardship for his people. Nobody likes rejection, but Jesus knew that it was the only way for redemption. He walked intentionally into this hardship, so that he could take on the powers of evil in all their intensity. And he knew he would overcome for us.