Why is my boss being like this?

This has nothing to do with dating but it does have to do with my bosses attitude. I started working in an animal hospital, where I known the doctor there for 10 years. I’ve been there for almost a month was getting decent hours and then randomly told the office manager. I might be exhausted and he’s cutting my hours back instead of talking to me about it I’m just frustrated because she never tells you how he’s very introverted And extremely weird. I expressed to the office manager. I don’t want my hours to change. She went to him and said if you change that she will leave he replied and said oh you told her He seemed really nervous and she goes. Yes I had to tell her he replied nothing set in stone. I don’t know what that means. I don’t know what I should do next and why you cut my hours all the sudden

Why is my boss being like this?
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