My guess is that the guy has made up his mind about leaving his wife after discovering shes been cheating on him.
"We cast a single shadow for so long now
It's so hard to see the sun at all! (The sun at all!)
But you need light to see
The writing on the wall!"
He realizes that, once they became separated, its obvious to him, or he sees the "writing on the wall", that they were never really meant to be and they never got along very well in the first place, and its actually for the better.
My guess is that the guy has made up his mind about leaving his wife after discovering shes been cheating on him.
"We cast a single shadow for so long now It's so hard to see the sun at all! (The sun at all!) But you need light to see The writing on the wall!"
He realizes that, once they became separated, its obvious to him, or he sees the "writing on the wall", that they were never really meant to be and they never got along very well in the first place, and its actually for the better.