I make the assumption that you are referring to the time Moses was with God in Horeb, the mount of God.
Exodus 24:18 And Moses went into the midst of the cloud, and gat him up into the mount: and Moses was in the mount forty days and forty nights.
God did not separate himself from the people.
God came down on the mount Horeb and remained there.
Moses went up into the mount to speak with God.
God remained in the mount for the forty days of Moses’ first visit and was still there when Moses went up a second time for a further forty days.
The only separation was that of distance.
A boundary was set around the mount, because the place where God places himself is holy and the people of Israel were not holy.
The people were in no doubt about the nearness of God during the 40 days and nights.
I hope you find this helpful.