Is it considered backbiting for a girl to tell her friend that she has come to dislike her fiancé because he tries to call her all the time and is rushing their relationship?

If the girl's friend knows her fiancé, then speaking about him in a way he dislikes constitutes forbidden backbiting for both the speaker and the listener. However, if she does not know him, or if she speaks vaguely about him without identifying him, then the speech is not considered backbiting. It must be emphasized that the fiancée is considered a stranger to her fiancé until the marriage contract is concluded, and it is not permissible to speak with her except out of necessity and while observing the Islamic guidelines.