Okay, I have been looking for this song for a couple days and am starting to lose my mind. I trully believe it is and ending song of an anime, I already asked AI, Shazam, and other sources, didnt find anything. This is what I know:
The music ends with something like "in this eternity" or "eternally", in english, important to note it is not only the ending of the singing, the music ends a few notes after the lyrics, I remember there is piano notes on it as well. It is sang by a female singer, its a slow passed ballad, and I remember it being mostly white. If it is really from an anime, I believe it to be most likely from the early 2000, because thats when I was more into anime. Also, it is not from Wolfs Rain or Gundam Seed, neither from a newer anime, already looked.