10. Sam Malone and Diane Chambers
Portrayed by: Ted Danson and Shelley Long
The first sparks between the explosive couple were born out of bickering and even after they finally consummated their love-hate flirtation, Sam and Diane continued to spar. Most of the time their constant conflicts provided the heat that kept their relationship alive, but come finale time one would get fed up past the point of immediate reconciliation with the other, igniting an on/off pattern that continued until Long left the show after season five.
The mismatched pairing of womanizing athlete/bartender and intellectual waitress was always doomed, not because they couldn't commit to each other, but instead because they were too insecure to believe that the other would.