if I ever put my academic ahat on again, probably one of the first papers i will write.

You should - you should!

I, too, think his ending for Arwen is cruel - and it would have taken so little change for her ending to be happier - to simply allow her to chose to 'stop' just as Aragorn was able to would have been a fitting end. To cause her to suffer and despair seems so sad, and really has no bearing on the main story at all.