The problem for highbloods was that it was incredibly hard to find a kismesis or matesprit that could live as long as you. Even if the hemospectrum difference wasn't challenge enough, the thought of a quadrantmate dying was enough to turn most highbloods away from any type of romance. The tales told to wrigglers were of trolls beating their blood colors and living together happily for thousands of sweeps. Unfortunately for Eridan and Sollux, life is not a fairy tale, and nothing lasts forever.