This Whole test sing is Literal regret!
The song is actually called regret though. For an entirely different reason though.
The original test record (which was ongoing from start to finish, just cropped out my shenanigans) was about 6 min.
Once I finally nailed the beginning, I added the actually song behind it and was able to continue nailing the beginning with some back vocals!

At some point I said "Dōshitemo inai kata" ( どうしてもいない方 )
I was going to say Dotchimichi (どっちみち) behind that, but never did.
It means " If you do not have absolutely any way." As a joke to the fact I couldn't say Dōshite ano

Translated Lyrics that I wind up singing over and over again:
The scenery outside the window changes
As the seasons themselves leave me behind
You were always there for me to quell my anxiety
Why couldn't I see it back then?

And as you slipped from my sight
The only thing I couldn't bring myself to say was "Don't go"