Jeremiah was not an exception to this. Considering that he was chosen by God to be His mouthpiece, he was least expected to feel this way. But Jeremiah started to doubt God when he mentioned this :
Why does the way of the wicked prosper?
Why do all the faithless live at ease?
You are always on their lips
but far from their hearts.
You have planted them and they have taken root
they grow and bear fruit.
(Jeremiah 12: 1-2)
A question filled with doubt unexpectedly expressed from a prophet like him.
When did Jeremiah started to feel bad? When Jeremiah started to compare. When he saw that the wicked people around Him is still experiencing blessings inspite of their unworthiness. And He was disappointed with God because of that. He forgot that God's way will always be higher than ours.
Comparison will always cause insecurity, jealousy and many other feelings we never want to feel. So instead of looking to the right or to the left, look up, straight to Him. You'll never go wrong in doing so. (: