Do you know why she does not like to visit him? If he is safe and his house is safe, you should do everything you can to encourage the relationship. She may be taking on your negativity or he may just not be a very attentive parent. Help him be a better parent by role modeling for him and discussing this with him. Maybe they could go to counseling together. Teenagers often do not want to be with either parent. It is important, however, to provide ample time with each parent.