It is interesting to think: Why are we separate? Why don't we feel what others feel? One answer I have contemplated is that Hashem, Who feels what we feel, hides Himself in order that we may receive a reward for seeking Him. We as people can seek each other out to good deeds for each other. Were we to feel one another's pain, we would immediately run to help each other. Instead we must work to feel each other's pain and arouse ourselves to do kindness towards one another. Thereby we receive a greater reward for helping each other.