Moms are always worried about their kids; it’s almost like a second nature of theirs because they always wish for what’s best for their children. In fact, they would go to any measure if it’s for the benefit of their child, even get friendly with their ex’s new girlfriend.
Such was the case with today’s original poster (OP) who found out that her controlling ex-husband often left their child alone with his new girlfriend. She felt that the woman was not mature enough to parent her daughter, but she still tried to build a relationship with her, just for the child’s sake.
More info: Mumsnet