Originally titled “This time”, the title was altered to reflect the tenor of the verses. The song was constructed chorus first, with the verses constructed as similes.
“She’s” (in the title) cleverly binds present and past tenses. And so can be correctly construed to mean “she is” and “she was”.
She gave my life meaning
She was the reason that I lived,
When she left …
She was the best thing in my life,
Now she’s gone I cry at night.