From Y to Y

I've always loved this song, even before I found Clear's cover of it. The way I interpret the title, is that 'Y' stands for 'yes'(relationship), and that since the person singing does not want the relationship to go from 'y to z' (to end), she/he keeps believing in 'y to y'. I think I might've born that interpretation from a comment somewhere, but I don't really remember. I still listen to this song.

 

Original song

romaji and translation