Not knowing God can cause much unhappiness. For example, you can feel lonely and become over-attached to a pet. There are even men who spend thousands of dollars to buy a life-size silicone doll to be their make-belief wife. Others feel self-pity or the emptiness of life and are driven to drink at the bar. Jealousy, envy, anger, intolerance and the like are all symptoms of unhappiness.
The good news is that once you have established a good, close relationship with God, everything gets straightened out. To me, the best part is not seeing that you are now a better or worse person, but that you are important to the Father and you are loved by him.