It's If you leave before me by Mike Ness
Here's one by the same Singer but from the band he is famous for.
I was so blind
I was so wrong
The day we met it never leaves my mind
I thought you play some foolish game
But now my heart tells me I was wrong
Hahahaha Ok.
Let's see how about
If you leave this world before me
I promise to you I shall keep
I won't fall in love with another one
Over your ashes I shall weep