Donovan McNabb and Terrell Owens
This one is actually a little bittersweet, since this quarterback-wide receiver relationship had serious promise. Neither T.O. nor Donovan ever played better than when they shared the field during the 2005 season, making it all the way to Super Bowl XXXIV, Owens playing in the game in spite of a serious injury.
After they lost to the Patriots, though, T.O. started trash-talking his quarterback, and the feud escalated until T.O. was suspended and then released by the Eagles. T.O. next went to the Cowboys, making him Tony Romo's problem.