I had the same thing happen when I was working for a payday advance check cashing company. I worked with a lady manager for about three months, and unlike your experience though, we became great friends in that time. However, in only a short three months our regional manager promoted me to manager of my own location. BOOM! She had a real problem with that and the friendship vanished and proved how real it wasn't. She instantly was not there any more when I tried to call her store with questions. Instantly upon taking location manager I was on my own. But, I did it and my store was running GREAT numbers and her numbers were not so good and her customers straight told her that they were not returning because she was becoming grouchy and irritable and the cheerful lady was no longer there to wait on them. She actually ended up losing her job and I got a raise because my numbers just kept running well, even during tax season, and in the payday advance business that does not happen. That is the time when people do not need me.
But, oh well, that is my nickel's worth, and I have rambled on enough. Just my link to the chain.