I’m a high school teacher, and every year I have students who want to be called by a different name, usually female transgender students who want to be called by a male name. It’s not hard to do that, and it doesn’t matter to me if they want to go by a different name. That’s a small gesture to make to make someone feel supported. If I can do that for students I barely know at first, I don’t understand why she wouldn’t do it for someone she’s in a relationship with.