What ayu song is this?
 

I can't think of the melody or the romaji, but I can think of this snippet:

"I'm sorry I didn't see your pain back then..." or something like that.

Pain might also be tears or despair or something. Not a lot to go on, but thanks for any help!

MOON?
"I'm sorry that I didn't even have the courage to softly wipe the tears"

FRIEND II?
"I'm sorry for not feeling your pain."

YOU?
"You must have been hurt and tired
More than everyone thought you to be
I'm sorry for not having noticed it"

^^Thanks for that! It might be one of those...I only randomly thought of the lyrics and wanted to know what song it was. :)