. . . in Tolkien's world. Nor are there any reported births out of
wedlock, except among the orcs or the unfortunate men reduced to the level of
orcs. Among the free peoples, monogamy is so strict that there is only
one reported incident of a widower remarrying (Finwe, Feanor's father), and
that turned into a disaster (by making Feanor insanely jealous of his
stepsiblings). In several cases, including Arwen's, the mate left behind
goes off somewhere and dies of grief.
So not only is Aragorn faithful to Arwen, but the people of Middle-earth would
probably look at you with a blank stare if you tried to explain the concept of
being "unfaithful." And if Eowyn had known Aragorn was betrothed it
probably would not have entered her head to make a play for him
anyway.
________________________________________
"‘I think he was a silly little man,' said Councillor Tompkins. ‘Worthless, in fact; no use to Society at all.'
"‘Oh, I don't know,' said Atkins, who was nobody of importance, just a schoolmaster. ‘I am not so sure: it depends on what you mean by use .'
"‘No practical or economic use,' said Tompkins. . . .
. . .
"‘It is proving very useful indeed,' said the Second Voice. ‘As a holiday, and a refreshment. It is splendid for convalescence; and not only for that, for many it is the best introduction to the Mountains. It works wonders in some cases. I am sending more and more there. They seldom have to come back.'"