Treat your friends well. Friends are friends as long as you treat them like friends. The moment you fail to forgive, fail to show mercy, or even fail to share is the moment you make your best friend into your enemy.
It’s not that your lack of compassion and kindness will offend your friend, though there is that. The problem runs deeper: Men are not inclined to die quietly.
When you fail in friendship to share and show mercy, you require that former friend to fight you to survive. That choice adds insult, so such friends won’t object to fighting.