I was reading a song's lyrics and I came across this sentence that I find a bit strange, probably cause I'm not analyzing in the correct way:
if I was just the ashes and you were the ground
and under a willow they laid me down
there'll be no trace that one was once two
after I fade into you
Isn't it neccesary to add a relative pronoun like "there'll be no trace that one WHICH was once two"?