Robert Crawford - Song #5.

Never remember what love's been,
That is the sorrow the world knows;
Forget it, or the heart too keen
Will ache and ache to the weary close.
Harden the heart even to love,
Or the change in the tender eyes
Will more than hate or passion move
The tears to fall, the wrath to rise.
Once the change comes, dare to forget
The sweetest truth you've dreamed of her,
Or the heart will so fret and fret
That it will have no comforter.
Turn not on love in the heart's despair,
For e'en her smiles were bitter then,
When all her faith is light as air,
And all her ways are hers again.

Robert Crawford

http://www.poemhunter.com/poem/song-5-6/