I've had friends(and family) betray me, steal from me, break stuff and never aplogize, borrow mounds of cash and pretend that it never happend, get stood up, offer the labor of my back 100 times in moves and whatnot and rarely ever been helped back in like kind... but they have all remained largely my friends for years and years while being semi two-faced before I end up making the decison to treat them exactly as they treat me... which causes some quick reactions at times and clouds of dust as they run over the hills never to be seen again. The last major friend was cast off because they would demand so much from me and insist that I keep going downtown to visit them each and every time. He would never come to my place. 50% of the words out of his mouth would be in lament for his mothers death 20 years prior and his hatred for his dad. He loved to quintiple repeat himself. It took a while... but grew very old in time. The last time I spoke to him, I asked him to visit me where I lived for once. He flat out refused... so I cut him loose.
The one major thing that will get you dismissed from my roster is to become incommunitcative. If I make 3 attempts at contact that are never returned... legit attempts at contact; emails that I know were read, phone messages that go unreplied to... I will no longer attempt to contact again unless that person can give just cause for such extremely rude behavior... especially for one that calls themselves a friend. My position is that such people are never worth it. Thats how a good many internet friends go away... merely fading slowly away until communication ceases altogether.