Z
I was reading this interesting book called How to handle adversity for Dr. Charles Stanley. The book mentioned what you've mentioned here that YES God feels and understands our frustration, hurt and grief. When Lazarus the man whom God LOVES got really sick, God didn't go to heal him right away but rather waited till Lazarus died and decayed THEN He went. And although God knew He will bring Lazarus back, yet, God wept!!!! ALL of this to say that sometimes God would interrupt our health or happiness for the sake of a greater goal. After ALL of that, God raised Lazarus from the dead and God's glory was crystal clear to the whole world. Imagine if God had gone and healed Lazarus right from the beginning, His glory won't be as big and clear as bringing Lazarus back from the dead and after being decayed, right? See the difference? It's NOT about us. God uses us for His glory.
God is faithful in His promises that He won't test us more than we endure BUT we do not know how much we can take. We might think this is as much as we can deal with. That's what WE think. God KNOWS exactly how much we can endure and how far He can push us. So because sometimes there's a difference between what we know and what God knows, we think that God did not keep His promise when He actual IS keeping His promise.