The song is sung by a single female, in English.
There is only one minor and distinct feature of the song besides how beautifully it is sung.
That is, the context of the opening explains that it 'feels like they were still sitting on the bed'.
I am certain 'bed' is therefore part of the lyrics, but there's absolutely no other clues I have.
Everytime I search I don't come up with anything.. It has been years, I still remember the feeling of the song and the beauty in the voice, but it's as if I'm not, somehow, allowed to listen once more.
If it helps, the last I can recall having the song play to me was from my computer back in 2004-ish.

Truly apologise for not having better leads, I would say it'd have to be pure chance that somebody that recognises the song passes by this post.

Thank you for reading. I appreciate you..