If the lover is the Lord and his beloved his Israel-church, then there are rich possibilities for thinking about additional meanings for these phrases.
The Lord’s partial or full invisibility to us is one: he is there and can see us, but we cannot see him.
The Lord may seem to choose to conceal himself from us: he “stands behind our wall” (a word that occurs only here in the Song). But this is a barrier we have erected, and its presence here may suggest that it is our actions rather than the Lord’s that separate us from him.
We have enclosed ourselves by sin in a place in which the Lord’s voice can be heard, yes, but where he cannot be seen. There are, however, openings even in this wall, openings that let in the Lord’s light. Through those openings he approaches more closely to us, and through them he speaks to us.
On this reading, scripture itself, and especially the words of the Song under discussion, serve as just such openings: in reading or hearing the Song we are looked at by the Lord as our lover through the windows and latticework of scripture.
A conceit, it may seem, but a nice one. The Song here performs what it figures: an opening to the “voice”—and proleptically the vision and the touch—of the Lord.