The cutest pair of straight 14-year-olds I currently know of, Fuu and Ferio have it all. The cross-dimensional aspect guarantees that things will be difficult, important in any relationship, especially one as outwardly perfect as theirs. Their names match, their weapons are similar (they carry the two biggest swords of the first season,) their personalities complement each other, and they're even color-coordinated. The only couple that even comes close to matching as well as they do on an aesthetic level is Ashram and Pirotess. And besides, they're just CUTE. Kawaii, even. In one scene, Ferio gives Fuu the thing that will let them keep in touch. Umi demands to know "Why'd you give it to her?" He replies "Because I love her more!" and Fuu bursts into flames momentarily. One of the coolest things about their relationship is that while in his own way he's quite chivalrous, he also respects her as a fighter, rather than treating her as a lady on a pedestal.
Fuu Gallery - Manga scans! Yay! There were some other things, too.
And, er. Those were about all my sources. Presumably a few came from the Image Archive (we all know which one I mean; 70+ pages of FY screengrabs... yeah.) but as it's a dead link at the moment, I'm not including it.
