Why is fear a part of love?

The fear of finding it.
The fear of losing it
And never finding it again.
They say that birds and wolves
Mate for life.
Why can’t humans?
We are so afraid of ourselves
And things we can’t show others
That we end up offering so little
Of ourselves
Just when we need
To offer the most.
Like a bird I fly,
I soar far away from myself
And like a wolf I smell the air
And creep back slowly.
Perhaps fear is a part of love
To make it stronger.
I don’t know.
I only feel the fear.