I think it depends on where you are.
If you're talking northern Dunedain of the Angle, then
probably you're in a Dunedain settlement and
probably you've married another remnant of the Dunedain people.
The Dunedain of late Third Age Eriador strike me as a people very much aware that they're a dwindled remnant of what once was, and I suspect most given the opportunity would marry within their own people so as not to fade away entirely.
If that wasn't an option.. then a man of the Dunedain might find a wife among the Breefolk - or perhaps a daughter of one of the shepherds that (I think?) Aragorn mentioned along the Great East Road.
edit: what we see of Eriador really reminds of the far-out regions of the Alaska bush. There's scattered settlements, you can go weeks without seeing another soul - but everyone knows "oh, so-and-so lives way out past that hill over there, about a day down the river after you pass the big sandbar." It's far too empty to have anything like a "small town" vibe, but folk still have a sense for who's where, and who to seek out in times of trouble.
Gondor's another matter entirely: Minas Tirith is a comparatively cosmopolitan place, with (if I recall correctly) maritime contacts all along Belfalas and DolAmroth, and is surrounded by farmed country. There's a great many more people there, mostly I think a long-ago mixture of Dunedain and native stock of that region.
edit - eek!
re-reading, looks like Udwin beat me to everything important. Figures.
![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
Persona: Aerlinneth, Dúnedain of Amon Lendel c. TA 3010.