Do you understand death to be "separation"?
THis is an edited version of my previous post. The time expired and I could not complete the edits to that previous post.
Death is when something no longer can do what it is supposed to do when alive/live. It is not responsive to that which it used to be responsive. A person is dead to the world when they are asleep and no longer responsive to the world. A nerve is dead when it is no longer responsive to the needle inserted into the nerve. A body is dead when it no longer responds to external stimuli, A radio goes dead when it stops responding to the broadcasted radio waves. There is not necessarily separation between the dead thing and the external stimuli. The radio waves are touching the radio receiver, the needle is touching the nerve, the sleeping body is integrally connected to the world.
So, we could perhaps translate Gen 3:3-5 as, "... in the day you eat of it, to die you will die
(or, in the day you eat of it, to become unresponsive you will be becoming unresponsive.)
God did not actually separate from man when man sinned. God is not so fragile that He will become defiled through contact with sin and sinners. Jesus did not become unclean when He touched the unclean; but the unclean who experienced His touch became cleansed. What happened with man sinning was that man became less responsive to the physical creation and to God, and this degradation of responsiveness would lead to complete unresponsiveness toward the physical creation in physical death, and the complete unresponsiveness toward God of a completely calloused heart that denies the reality of God's spiritual realm.
But to describe this as separation, I think, is misleading, because even the unresponsive live and move and have their being in God, which does not sound like separation to me. Our sins separate us from God. Because of the guilt and shame and/or pride that results from our sin, we feel separated from God. but our sins do not separate God from us. God is bigger than that. God is incorruptible no matter how much sin He is in contact with as the sustainer of the universe.
The unresponsiveness of "death" is sometimes a result of separation, but not necessarily so.