Was the Bride Ever Reveled in the Manga, and if she was why doesn't the page say who she is? Are we waiting for the Anime to Reveal it?
Just wait for the movie.
I posted my own theory. (rewatch the last episode you can hear the girl who kisses Futarou grunt and it sounds a lot like Yotsuba). And as he/she said wait for the movie!
What do you think?