The Degradation Factor in Friendships

The study also showed 40 to 60 hours to form a casual friendship, 80 to 100 hours to be upgraded to friend and 200 hours to become good friends. I wonder what the degradation factor is in this, because I've got mates like in Australia who I might see any every couple of years for like a few hours. Is there a point at which when you reach a certain level of activation energy that the bond cannot be undone?