I think he's putting TOO much of the burden on YOU, when you are not his daughter's mother, you are not married, and you are not co-parenting.

It's his daughter who is acting out and who is having problems with you. I don't think that is your burden to own all by yourself.

He's asking you to take on a co-parenting role, when you are simply a girlfriend. That is not fair and it's putting FAR too much of the burden all on you to resolve his daughter's behavioral issues over a divorce and a new gf.

It's not that simple. That's why I say it's HIS responsibility. He's the parent, he got divorced, he should be dealing with his daughter's issues himself as the SOLO parent in this equation.

It's a shame to me... you are left struggling with this all by yourself, and are trying to resolve it all by yourself. That makes me feel very sad for you.