When she's alone she can feel it pressing down on her, the pure bliss of Heaven. It hurts. Even the memory of Heaven's ecstasy is too much for one human body to bear. When she's alone, and she prefers to be alone, she drowns in that almost pleasurable agonizingly painful intensity. She can't give it up. Without her memories of Heaven, she wouldn't feel alive.
She knows she's selfish, wishing she were dead, and so, unselfishly, she wishes for more. She tells herself she could endure the agony of Heaven's ecstasy if she could have all this and Heaven too.