[The Saucepan Man]

But Luthien requested mortality and Arwen chose it. They were not prevented from entering the Blessed Realm against their will since they knew the consequences of their choice. Moreover, I would speculate that Arwen might, had a ship been available to take her, have been permitted entry following Aragron's death, although being mortal she would have died there like Frodo, Bilbo and Sam.

Mithrellas would not have been denied entry against her will although, had she made the same request as Luthien, it might conceivably have been granted.

Of course, by the will of Eru, I suppose anything is possible ...