Disclaimer: I don't own Hetalia.
It's not what they deserve; he's waited too long for Ludwig for this to happen. They deserve a fairytale. They deserve forever.
But the people of Italy can no longer support the weight of Germany's lavish daydreams. They starve and they wither from sheer distress at Germany's weight and they die.
It shows; Feliciano's face becomes like Ludwig's by the day, gaunt and severe and tired.
Feliciano does not have an eternity to give anymore.
The people of Italy riot; the people of Italy cry out under the duress of being allied with a vicious, war hungry Germany that slowly destroys itself in the end.
Feliciano can no longer keep his promises to Ludwig because Germany cannot keep its own vows. This new, glorious Germany is crumbling, and the remnants begin their descent into the abyss of history.
It is Feliciano's duty to ensure that Italy does not go down with it.
He'll regret this. There is no doubt that he loves Ludwig.
But I am Italy before I am Feliciano, he writes that night in his last letter to Ludwig, watches his tears blot the paper, and can't help but wish it wasn't true.