Yup ~ the sadness of the ultimate sadness is you won't be there to feel it. Or, the happiness of the ultimate happiness, or the love of the ultimate love, ...... cannot even be fully contemplated from this side of eternity.
And we miss the ones we miss, even for ages.
Leastwise that ALWAYS causes me to think that way when I hear that song ~ so I avoid it. But today I played it. And there it is.
George Jones could have written Ecclesiastes I think.
You are absolutely right. That song can be appreciated on more than one level. It is the saddest song I have ever heard.