There are times when a person knows both a bitterness and a joy of soul that cannot be shared among humans. It is not that people do not try to empathize and sympathize with us, they do. It is just that certain experiences and certain things go so deep within us that the only One who can comfort and the only One who can understand is God Himself.
The heart knows its own bitterness. There is a pain that we can feel both in our physical realm - but much more - in the spiritual realm that is very deep. It is so deep that we need more than human comfort to deal with it. There are times when we face serious issues (often life threatening issues) that although we are possibly surrounded by human comforters, we need a superhuman comforter. It is in those moments when only God can offer us the comfort that we desperately need. The main reason we know this is because of how God used David to write songs about these moments.
Too often we forget that the recording studio that God used to record those songs were times of great suffering, sorrow, and trial. In those moments David expresses a depth of bitterness and sorrow that few have ever touched. He says things to God that make us step back and gasp when we read them. Truly he is in a "bitterness" of soul in the midst of such suffering and trial. And Job reminds us that when a man is suffering his words are like the wind. David is bitter of soul at times in the Psalms, but it is also in those times that he cries out to God with a passion that we may not know either. Remember this, it is those who go the deepest in suffering, sorrow, and struggle - who also know the deepest levels of passion for God.
David cries out to God with a bitterness of heart that can only be healed by God Himself. Actually, it is a blessing when God takes us to such depths because often it takes that kind of situation to make us wholly dependent upon Him. We see that, indeed as Jesus has told us in John 15, "without Me you can do nothing." In that moment of complete helplessness we cry out to Him as we've never done before, and we find that He is also, indeed, able to deliver to the uttermost!
Thus we come to the second half of this proverb. A stranger does not share its joy. David not only speaks of the bitterness of heart that comes with excruciating trials, he also speaks of the joy of God's deliverance from those trials. After coming through some fairly deep trials and sorrows I've begun to touch the hem of the garment of such joy. Just as I cannot grasp the cries of David in his deepest pain, there is also a tinge of realization as I read the Psalms that I'm not sure I am getting the fullness of His joy either. A stranger to God's deliverance will never share the joy of knowing that God is the One who not only walked in the midst of our firey furnace, but He is the One who kept our clothes from being burned - or even smelling like smoke.
Oh, the joy of those who know His working. Oh the joy of those who know when He Who took them into the depths is also the One Who will bring them out again. Oh the joys of the ones who know that He will wound us, but He will also heal us. Oh the delight of soul that comes to the one who knows a depth of pain and bitterness of heart that goes beyond human comfort - but who also knows the only One Who can reach beyond human comprehension - beyond human ability - beyond mere human comfort - and can touch our deepest and most bitter wounds and heal them. May God bring wisdom to you this day, dear saint of God, and may He be your Deliverer and Comforter in your every distress!