I went through something like this with my ex. One day, she was fine. The next day, it was all about The Beatles conspiracy theories which never seem to end.

I went through something like this with my ex. One day, she was fine. The next day, it was all about The Beatles conspiracy theories which never seem to end. Ever. I stuck with her for two years before finally, reluctantly, leaving. We divorced a few years later, by which time her psychotic break had finished. It was truly awful. I didn't understand it at the time, and was angry then guilty. I should have dragged her to a hospital for examination, but I didn't. Get your friend some professional help.