I was going to say Urianger and Moenbryda but we all know how that turned out... I really liked the pair from the archer quest line, Silvairre and Leih I think? And Tataru and Wedge! Aymeric and Lucia too seem like they could be awesome together...

B-B-But my heart still breaks over Raubahn and the Sultana, huge guy/tiny girl be damned. TT_____TT