[Mithalwen]

But they don't give formal vows that I recall. Didn't Elrond discourage it? Gimli specifically, a warning the dwarf only understands as he leaves Lothlorien in part of one of my favourite passages in all Tolkien "“Torment in the dark was the danger that I feared, and it did not hold me back. But I would not have come, had I known the danger of light and joy. Now I have taken my worst wound in this parting, even if I were to go this night straight to the Dark Lord. Alas for Gimli son of Glóin!” They agreed to go to the passes of the mountains ans maybe beyond. Even Aragorn did not know Gandalf's plan beyond Lorien because it didn't involve him.