My partner of almost 2 years has 2 girls. Ages 9 and 13. The 9yo is very caring and loving but has an attitude the age of a 19yo and the 13yo is stubborn, selfish and lack empathy. I truly cannot find something nice to say about her. We've had talks with the 9 yo and her attitude has improved but there are times she loses herself (I can cope with that- I just remind her why her behavior is not acceptable). The 13 yo remains a challenge. She stays in her room dancing all day, she's unkind, uncaring, she only gives if she is getting in return and she doesn't care if you're hurt. She doesn't bring in the grades and if you tell her to do anything around the house she ignores and throws tantrums and spiral into a panic state and shuts down. At this point her mother just leaves her alone or if it's really bad, her mother will quarrel for her to get things done regardless of her shutting down. But then my partner feels bad about her daughter outburst so she goes and make up by buying her sweets or telling her to invite over friends. These behaviors are concerning. Her mother knows her behavior is off. We've gone as far as to enroll her in therapy. Nonetheless, I talk to her mother and she gets defensive. Her way of dealing with the disobedience is shouting and taking away devices. She doesn't beat but likes to say she will and it upsets me because she lacks control. I'm a dominant person so id shut this down long time but I cannot. I keep telling my partner I don't know how to navigate the relationship with her 13yo . Lately, I often find myself asking if I want to stay in their lives? If my answer is no. That means I will have to leave my partner and that's what I am struggling with.