My daughter read the books in the first grade. She also read the appendices. She thought Arwen & Aragorn made no sense:
“What would someone who was over 2500 years old see in a 50 year old human?”
Hmmmm...just how serious would someone born in 700 BC feel about a human being born in 1960? What would they talk about? Auden, and my daughter, were right!
I think your daughter put her finger on the crux of the matter, and it's central to Tolkien's overall case for Middle Earth - how, indeed, could a society that ancient have any regard for the ephemerals to come? The Third Age was, after all, the time of the humans, such as they are. The ancients must board their ships and sail to another place. Very few of their companions could contemplate coming with them: Bilbo, Frodo, of course, who made a similar sacrifice themselves, Gimli, Elf-friend, Gandalf, and the list is short or unknown from there. Frodo in particular, who gave up everything to keep it safe for someone else, is perhaps Arwen's counterpart in sacrifice. And it is her place on the ships that he took IIRC.
What then of her? What of a love that would have her give up immortality for a few brief years of companionship with the beloved? It is not inexplicable, I think, it is Tolkien's very deepest commentary on human relationships, deep enough to have it carven on his and his wife's gravestones in the terms of Beren and Luthien. It is, among the many mysteries of Middle Earth, the deepest of them all. I can imagine a Lord Of The Rings without it, but it would be a lesser work. Just my $0.02.
Uh, no.
Have you read the Silmarillion , the unfinished tales by Tolkien and the Bible,too? When you have both of those books in view, Tolkien explains that the elves in some ways envied man’s mortality. The elves had to live in a cursed Middle Earth, where they knew they would be defeated by evil. Humans would pass to the Undying Lands upon death.
However, Aragorn was more of a believer in eternal hope than Arwen, iirc.
There is more depth and much poignant background in Tolkiens writings on Middle Earth that is not fully described in the Hobbit and LOTR.
Someone on this thread just mentioned the Christian ethos in 1 Cor 13.
Also, there is the figure of speech;
“It is better to have loved and lost than never to have loved at all.”
In heaven, my wife and I won’t be married anymore, but I am certain that being married to her for several decades makes sense — on many many levels.
I bet a sharp person could write a whole book on the topic of Tolkien-Auden-humans-elves-death-immortality-Middle Earth - heaven - Christianity vis a vis skepticism etc etc.