If one of the parents was breaking down in grief, and unable to function, then CPS would make certain that the kids had someone in the family to take control, like the other parent or a grandparent or an Aunt. But to cease contact with that parent, makes me believe it is something other than just a parent having grieving issues. JMO
I had a friend whose child was dying of brain cancer, at age 5. She was inconsolable, and virtually useless as a mother for her older children at that time. Even after the funeral, it took a full year for her to snap back. Her husband did the best he could, but had to keep his job for the benefits. Many of us in the neighborhood pitched in and helped the grandmother with the two older elementary school kids. CPS was never involved, even though the older daughter would break down and cry at school, and was unable to really take part in class.