Tanto quanto posso dizer, as evidências (do LotR Apêndices) é:
Rómendacil showed especial favour to Vidugavia, who had aided him in the war. He called himself King of Rhovanion, and was indeed the most powerful of the Northern princes, though his own realm lay between Greenwood and the River Celduin.29 In 1250 Rómendacil sent his son Valacar as an ambassador to dwell for a while with Vidugavia and make himself acquainted with the language, manners, and policies of the Northmen. But Valacar far exceeded his father's designs. He grew to love the Northern lands and people, and he married Vidumavi, daughter of Vidugavia. It was some years before he returned. From this marriage came later the war of the Kin-strife.
'For the high men of Gondor already looked askance at the Northmen among them; and it was a thing unheard of before that the heir to the crown, or any son of the King, should wed one of lesser and alien race. There was already rebellion in the southern provinces when King Valacar grew old. His queen had been a fair and noble lady, but short-lived according to the fate of lesser Men, and the Dúnedain feared that her descendants would prove the same and fall from the majesty of the Kings of Men. Also they were unwilling to accept as lord her son, who though he was now called Eldacar, had been born in an alien country and was named in his youth Vinitharya, a name of his mother's people.
Parece claro que até aquele momento, casar-se com os Dunedain desqualificava a progênie do trono e isso não era um problema anterior e, portanto, presumivelmente, não havia sido feito.
Arwen não era numenoreana, mas seu sangue era superior do que a de qualquer numenoreano - ela era sobrinha de Elros, o primeiro rei de Numenor, afinal! e noldoriano do lado de sua mãe. Mesmo que alguém quisesse excluir seus descendentes, dificilmente conseguiria sucesso.