How do you know

A writer's block that I got after my girlfriend broke up with me

How do you Know?

The Heart is a fickle thing
it is the only organ
that may be touched by others,

It may be loved
It may be hated
It may be both at the same time,

It may be ripped from you,
Just at the moment you begin to love
It may even turn black at the thought,

You may love and get nothing back
You may love and get little back
You may truly love,

And get lots of love back
That is true love
You now find yourself asking,

How do you know?