What is an enemy (San 9b)

I've been in the following situation a number of times. I get in a fight with a friend. After storming off, I'm not ready to talk with this friend, so I avoid him. Days pass and still I am not ready to talk with him. Perhaps this is because I am angry or perhaps this is because I am too proud to apologize for my role in the fight. Nevertheless, I know that when we do see each other things will be fine, because throughout this ordeal we are still friends at our core.

Or are we?

According to today's daf (actually the footnotes on today's daf - the actual source for the following is found in tractate Sanhedrin) one turns from a friend to an enemy if you go three days without speaking because of anger.

The implications of this are important for Talmud's discussion surrounding the "city of refuge." In this case if you kill someone inadvertently, you may flee to one of these cities, however it gets a lot more complicated if the person you kill is your enemy.

Leaving this context aside, I think the idea of the enemy is very important. How many times have we actually turned a friend into an enemy because we went too long without speaking after a fight? The Talmud has created a countdown for us (a three day limit of silence). From the minute we part ways after an argument we have three days to make amends. Maybe if we follow this timeline we'll keep a lot more friends and seriously limit the number of enemies in our lives.