Kili and Tauriel.
I am very fond of defiant romances. These two defy their own races’ prejudices, their own individual expectations, and they also defy the movie goers who complain “but it didn’t happen in the book,” etc. Good for Kili and Tauriel! I personally love these two. He’s handsome, she’s beautiful, they’re both so very young and impetuous and wide-eyed about life... why wouldn’t they fall for each other? I love how they just open up to each other immediately, start telling and listening to each other's stories, how simple it is for them to start sharing things, even when one is technically a prisoner. They don't care and they waste no time. Their limited time together is delightful. They make me grin, which I can’t say for any other couple in Middle-Earth (well, except for Celeborn and Galadriel, but that’s naught to do with the two of them and is only because Marton’s on screen. I’m always grinning if he’s around.)
I also admit, I am very fond of tragic romances. Hey, what can I say? My first bondings with fictional characters in life were in opera and, while there are plenty of comedies and operas with happy endings, the majority I grew up did not end well for one or both lovers. Didn't stop me from loving the characteres, in fact, I just loved them all the more because their time together was limited. Also, my first Shakespeare experience was Romeo & Juliet, and that was a Profound Experience on my youthful, unsuspecting life, let me tell you. One of those moments in life so strong that the emotional impact has never faded. (Hm, randomly, I just realized I have exactly three novels with where the romance ends well. Out of nine. Um... yeah.)
So, yeah, I love Kili and Tauriel. I love that they don’t end happily, but they make the most of their time together. Their whole doomed romance just resonates for me.