Suboshi! It makes perfect sense...They both care about each other very much, although Yui doesn't realize this until it's too late. If Suboshi had lived, Yui and he would have been the most adorable couple! Of course, like Tamahome, there's probably someone that looks just like him and is a reincarnation of him in Yui's world. Wouldn't that be so neat?
I made these two images of Yui and Suboshi, since there aren't too many pictures of them together. Look, but please don't touch. (read: Steal and DIE!!) :
So, why else did I choose Suboshi? Well, other than the fact that he and Yui sorta look alike, you mean? -_-;; Heh...well, he's the evil twin (Amiboshi being the good twin), and evil twins are always nice! Besides, isn't he adorable? And he's the only guy that truly loved Yui for who she was, and not just because he was obligated to protect her by prophecy...If you'd like to read more about their love, there's more about them in the Potential Lovers section under "Case #3."