It kills me not to know

I don't know why I feel this way
It kills me not to know
For some reason
I feel like I can't live without you

My heart breaks,
every time you look at her
You may see a smile
But behind my smile you see
is tears of a broken heart.

But you'll never see how much you mean to me
Or will I ever get over
the fact the all we'll ever be,
are friends

I just don't know why I feel this way
It kills me not to know.