I don’t understand why this person would no longer remain your friend–could it be because you inevitably harp on this issue to the point where she becomes irritated and responds in kind?
This seems to be an underlying thread running through many of your posts, that people are stupid to ignore your Cassandra-like warnings. You could be right, she may be making a stupid decision, but as her friend I would think you’d make your argument and leave it at–unless you’re more interested in winning the argument rather than remaining friends.