Yes, in that way it could be AU. On the other hand, you are looking at the situation from the POV of the Rohan guard, and who is to say it was not a very vivid dream?

Clearly I have not made this obvious enough in the story, 'cause no one seems to even consider that an option.

I don't know why your other reviewer might consider this AU, but one possibility is that this definitely contradicts the information provided in Lore and Customs of the Eldar from The Histories of Middle-Earth: Morgoth's Ring. In this essay Tolkien makes it quite clear that Elves do not do that sort of thing. They consider intercourse as marriage, every bit as binding as a formal wedding ceremony, and have no concept of divorce. Even if one partner dies, the marriage still remains binding. But that is just why it is AU. It doesn't make it any less of a solid, well written piece of fan-fiction, even if I morally object to the situation. I suppose what I'm trying to say is that stylistically, you are an excellent writer, I was just a bit disappointed in the subject matter.

Enchanting.

A very nice story.
While reading it, I got captured in the thought 'what does she want?' (Refering to Elnarie, ofcourse.)
So, even while I was already forming some thoughts in my mind, on how the story was written, it kept me reading on.
And the end was a bit as to be expected (they ended up loving eachother) but with a nice twitch that leaves some guessing for the reader (Did it realy happen? Did he dream it all? If it happened: why?)
I personaly like the writings of Hemmingway quite much, and the way he describes things. In this story I see the same tendency: attempts to explain how things look and feel. Although I'd say that some things are a bit overdone. Maybe a bit too much 'forced', and thus introducing redundant information into the story that disrupt the smooth reading. Given the time and location where the story takes place, the author has chosen to write in a wee bit 'old' and maybe even majestic way. Which is a good thing. But the forced way of writing can easily be spotted.
The reader does not need to know every detail to creates a proper vision of what is going on. On the contrary, you can easily let out some details that will even invite the reader to step into the story and live it to the fullest. Not knowing leaves the possibility for own imagination. And that's the lovely thing of reading a story, you can dive in the sea of your own imagination and enjoy all you see there. Be sure to give the reader a hand to help him into that lovely place and not taking all possibility away by obsessively wanting to explain every detail yourself.
I enjoyed the story quite! Do not get me wrong. I just want to point out that you are on the right path but need to develop a bit more to make it perfect. Keep on going. I'll be very interested in more work from your hands.
IF it wasn't a dream, she might just have fallen for the guard, but probably had to leave again early in the morning with the other elves and didn't want to wake that hansome man. Or maybe she was scared? But of what then?

Very nicely written, though AU.

Oh - this was so beautifully written that I had to comment. You described the scene(s) through Arnwulf's eyes with great eloquence and a delightfully fluid style. I liked this story very much, especially the rather whimsical, thoughtful ending.

Just a tiny bit of nitpicking, which may well be a mistake on my behalf: Arnwulf describes Elnarie's hair as being "bound back by small plaits around her head". If that is so, then how could her hair be "flying over her shoulder with the sharp movement of her head" when she casts him a backwards glance? Does this mean that she was wearing her hair in a sort of 'Legolas-style'?

Apologies for the nitpick. I think you should submit this for the Challenge.

Good luck!
Salope