Why would a guy suddenly stop calling me by my name?

My male friend calls people by their names and he used to call me by my name as well. Suddenly he has stopped that. If he sees me he'd start talking to me and usually the tone is a bit different, I somehow always understand that he's talking to me. But why would he stop using my name? In fact he won't use my name while mentioning me in conversations with other people either. He'd say: "she said this", "I was talking about her" and refer to me, etc.

Please don't ask me to ask him. It feels awkward to mention it.

Why would a guy suddenly stop calling me by my name?
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