I own nothing.
They call it the Gift of Men, but when her parents and her people, especially her father, discovered that Lúthien had returned from the Halls "diminished", as Thingol put it, they were grieved indeed. They looked upon her as though she had told them that she had contracted some horrific, wasting illness, or as though she had said that she would withdraw to the furthest corners of the earth, and never have contact with them again. Melian shook her head and turned away. Thingol raged before slumping to his chair and weeping; no words could console him. Lúthien had felt their grief, but she could not understand why they felt that Men's was such a terrible fate.
Even before she met her love, Lúthien always had an eye for adventure. She can recall an image of herself as a little girl, wandering through the forest in search of new plants or animals that she hadn't seen before, trying to track down a bit of unfamiliar bird call or discover some secret pool hidden deep in the dense woods. As a young woman, she longed to see distant lands, longed to travel. She would have dreams about the edge of the world where the stars rose out of the sea and into the sky, gleaming like diamonds close enough for her to touch.
Lúthien is unafraid of death and what lies beyond it, waiting for her, mortal as she is now. Her parents grieve, her people grieve, for one still living as though she is already dead, but Lúthien can not believe that they will be parted forever.
Besides, she will not be alone. She will have her love with her, she will have every other mortal child of Ilúvatar with her, and Lúthien knows this, if she knows nothing else:
Death is not the end. Death is not an empty void. Death is a mystery waiting to be solved, an unseen land, waiting to be explored, and there will be far less grief for her in that unexplored place than there would have been in Valmar, if she had chosen separation from her love.