Jesus wept. That verse is commonly (and often comically) known as the shortest verse in the Bible; but it is certainly not the least significant. This expression of grief that Jesus demonstrates happens as he approached the burial site of one of his friends. While others took that to mean that Jesus really loved his late friend, the sorrow he felt was far deeper than that. He was grieving at sin and the consequences it causes; namely, death.
In Jeremiah 8 and 9, God shows this same heart as he mourns over his unrepentant people and the punishment they would soon receive. They no longer felt any shame for their sin, and they preached peace where there was no peace. They abused the law, using it to justify their own corruption rather than recognizing their need for God. He is so personally grieved, that he wish he could separate himself from them because of the pain they have caused him. He is sad that his very own people do not know him.
The story is the same today. We have grieved God because of our sin. If we only felt the extent of the pain that we cause him, we would desperately cry out to him to save us from ourselves and heal us. God invites us to identify with him in this sorrow and make the first step towards repentance. May we grow in our knowledge of him so that we may see through his eyes and feel what he feels and respond according to his goodness and grace.