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

She loves you very much and is not able to share your love with anyone. Kids do get possessive about their parents. Now, when she sees that your attention is not undivided towards her, she is not liking the whole situation. I think you need to be patient and talk to her calmly. More than anything what I feel is you have to make your daughter and your girlfriend open up with each other, spend time and your girlfriend will have to do efforts so that your daughter starts liking her, and do not see her a person who is taking away her daddy from her. And it will not going to be just an initial push that you spoke to her sorted things and you can be happy with your girlfriend. You will have to pamper and make your daughter feel wanted and express your love on daily basis. Your daughter is at a very nascent age and if she feels insecure in her own home, she may seek that love, attention outside and it may lead her into bad company and into bad things. So, I suggest, you should make your girlfriend interact with your daughter as much as possible. All of you go for picnics, trips, movies, do activities together, cook, play, help in her school work etc., so that she develops a bonding with your girlfriend. And once she accepts her in your and her life, things will become quite easy for you.