Disclaimer: I am about as un-authoritative as one can get to comment on scriptures with which I just barely familiar. I am also fully aware (and wish to alert the reader) that some of my logic here is circular - I accept this as being necessary given that faith and religion specifically deal with those things which are beyond the reach of experimentation and proof and therefore outside the scope of rationality.
Eventually Krishna left Vrindavan for Mathur. As he was leaving, His path was blocked by the gopis who refused to allow Him to pass until He assured them that He was coming back just after finishing His business there. Krishna never returned, and the people of Vrindavan were left in constant longing for Him.
As Krishna explains in his letter (delivered by Uddhava):
"My dear gopis, in order to increase your superexcellent love for Me, I have purposely separated Myself from you. I have done this so that you may be in constant meditation on Me."So I got to thinking about what this really means. I prefer to ignore questions related to literal interpretations if historical events - it may or may not be as recorded, my interest is in the reason why it was recorded and how this can be applied to understand our lives.
The poet Sextus Aurelius Propertius expressed in one of his elegies, "always toward absent lovers love's tide stronger flows." This seems to be a curious sentiment, but there seems to be some intuitive truth to it. So I wonder if the explanation for Krishna's leaving of Vrindavan might also serve to explain why we do not see God physically manifested here in our daily lives, running our Earthly affairs for us.
Since it is asserted that the way to return to God is through the cultivation of love and devotion towards Him, it would make sense for Him to assist us in the cultivation by whetting our appetite and then allowing our hunger to increase and using that to pull us back to Him. Like the smell of freshly baked bread that seems to draw one to it by smell alone.