My 10 year old daughter has temper troubles and behaves very rudely with my girlfriend. how do I find out what’s wrong?

the best way for you to connect with her is through an honest chat. ask her directly on what is it that is bothering her. does she feel that your gf will try and take away your love and you will love your daughter less? or does she feel that your gf is trying to take the place of her real mother? in any situation, assure your daughter that your love for her will never change and that she will always be your first priority.