Paired characters in LotR

[Fordim Hedgethistle]

It seems that there's a couple of ways of 'dividing' the few pairs we've looked at so far: by gender (men and women); into 'spiritual' or 'moral' and 'physical' or 'simple'; in terms of fulfilment and sacrifice(?).

Is there overlap? It seems as though the characters who are on spiritual journeys (as pointed out by davem) end up with sacrifice and no female, while those on more physical journeys/quests ens up with the fulfilling female.

But even as I write this it seems not to work. Aragorn's journey ends with the fulfilment of marriage and children, but his journey is as morally implicated as is Frodo's and there's no way we can call him a simple person like Sam! What's more, this pattern would seem to relegate women to the rather limited role of domestic "fulfillers" (to coin a new phrase). The purpose of the women is to be paired up with the appropriate male hero at the conclusion of the journey? I don't think there's anyone here who'd be terribly comfortable with this idea (or is there?).