#5 Matt Hardy and Edge
Possibly the most famous broken friendship on the list, Matt Hardy and Edge have done it all in the ring together. They travelled the road together, put on fantastic tag team matches with their respective partners and paved the way for the high-flying tag teams by throwing caution to the wind every time they went out to perform.
As Team Extreme, Matt Hardy, Jeff Hardy and Lita were a big part of this revolution, and Matt and Lita became romantically involved. It seemed like the perfect relationship. Edge, who was extremely close to Matt, had an affair with Lita which started the chain reaction that led to the implosion of their friendship.
WWE would let Matt go as he made this information public on the Internet. This was before the days of everyone knowing everything, so the WWE tried to limit the damage to their brand by wishing Matt luck in his future endeavours.
However, due to crowd reaction to the situation, and this making Matt Hardy hotter than a cattle brand, WWE hired him back, and the two went at it, trading real blows in a segment on Raw.
The feud would result in a series of matches, and it must be said that despite the actual hatred for one another, they remained as professional as humanly possible. It is a testament to them as workers and wrestlers.
Now they have both moved on; I do believe they are both civil but will never be as close as they once were.