I saw both of their relationships pretty resolved by the end, mind you (by canon standards=. HOWEVER, Mytho and Rue as individuals have more potential to grow (not just pairing wise. I mean, Mytho JUST became a person. Can you imagine that? And Rue JUST figured out she can love and be loved! This doesn't cut in their relationship). This I say as more of a Fakiru fan than I am of Mytho/Rue (I love both couples to bits, but post series I consider Rue and Mytho far more fic-fodder but not in the romantic sense, more other relationships?).