Can someone please explain what is the meaning of this poem what does the poem represent.

You Were My Everything

You were my everything;
Now you're gone.
I don't have the strength
To carry on.

Skies always seemed sunny
When you were here;
Now there's nothing but gloom
In my atmosphere.

I loved you so much;
You were all I had;
Now my whole world
Is depressing and sad.

I'd like to start feeling
Other than blue,
But you were my everything,
What can I do?