Honestly, I think neither are realistic. I don't think that Brienne and Tormund are appropriate for each other at all...people think Tormund's crush it sweet and they love him, I think that's why they think it would be good. But let's assume that those two characters are real, do you buy that a highborn, honorable, idealistic, educated, sophisticated, serious lady like her would be interested and could be happy with a guy, let's say who has been living on the streets all his life, who is illiterate, rude, doesn't care about honor or ideals at all...who is all about eating, drinking, fucking, fighting and shitting. That's not a match, that's absurd. It seems like something to root for only because it's a fantasy story and some people don't think about Brienne's character much and see her only as a strong warrior like Tormund and nothing else. And I think they see him as Brienne's equal only because they love the character.

But I don't think that Jaime and Brienne would happen in real life either, it's also not realistic. Mainly because men like Jaime don't suddenly stop being a jerk, turn into a hero and a true knight, dump their hot girlfriends that they have been in love with and hook up with an ugly girl whose face has been eaten -in the books-, heh. It's not realistic, it would never happen either.

But we know that GRRM has been writing them as an adaptation of Beauty and the Beast story. When I look at it this way, I like their story...not much in the show though, but especially in the books. Because it's an interesting adaptation and since beauty and the beast is actually a fairytale, the fact that it's not realistic doesn't bother me. I wonder what will happen in the end, will one of them die in the arms of the other like the beast dies in the arms of beauty? See, I watch and read them with these in mind. I always look at a story from the angle that the writer of the story wants me to look, I think that way stories become the most satisfying in the end. ;)