Girlfriend wants me to ditch my female friend, accuses me of cheating, is this a red flag?

I have a friend at work, my girlfriend has accused me of cheating on her. She says I should not have lunch with my friend and have no contact. She doesn’t even want me to say hello to her. Is this a red flag?
Girlfriend wants me to ditch my female friend, accuses me of cheating, is this a red flag?
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