[Atariel]

I think that the elves in the Hobbit were happy and all sing-song because the only trouble was the fact that the dwarves (whom they didn't like anyway) had lost all their gold to a dragon (whom they hated even more than the dwarves), but in the Lord of the Rings, there is a posibility that they will all die, and there is a certainty that both Lothlorien and Rivendell will diminish.