My Ex says she must approve of my Girlfriend who I live with.

My Ex tells me that she must meet and approve of my girlfriend who I am living with now. She states that it is law and that she can prevent the boys from being with me on the weekends that I have them. I have them every other weekend and Wed nights. I never miss my time and take them more than required. I pay all the child support and maintenance on time and never late. Does she have a legal leg to stand on? Boys come home happy and excited, from the great weekends we have together. Boys come home to there house, clean, fed, happy and healthy.