They spent the few days they had left together before Natsu had to leave to join the army.
When Natsu was still at war, Lucy received a letter from the army.
Dear Miss Lucy,
Your dear husband, Natsu, was a great soldier and a great husband. We're also sad that he had to leave.
Lucy knew what the letter meant. It meant that Natsu wasn't coming back. He had died fighting as a soldier.
~Back to Present~
Lucy stares at the grave one last time, and then she left.
Once Lucy left, there was a breeze that blew the flower petals into the sky.
"My dear Lucy, I hope you can forgive my foolishness. I hope you move on with your life and forget about me. I don't want to see you suffer for the rest of time. Goodbye." A voice said from the heavens above the memory grave.
There was a flash of light in the sky, and then it was gone.
The people went on with their daily lives, forgetting about the flash of light after it vanished.
There is one person who seems to memorize this event. It was none other than Lucy.
It seems that Natsu was finally gone from this plane of the living to the heavens.
Lucy went on with her life, but never forgetting the flash of light that proved that Natsu had moved on as well.