Are you friends with two people who've had a falling out?

I haven't been in this position since high school so it's a bit disappointing that it's happening now. I don't have many friends, so I'm protective of the friendships I do have and am cautious about doing things that could lead to a rift. But my best friend has a tendency to get into fights with people and push people away. He's already estranged from his entire family and now he and his second-best male friend (who is also a good friend of mine) have had a falling out. Of course I feel like I'm the one who's going to have to repair things, not that I can even do that or should, but no one else is going to...