I think in the earlier chapters, if I remember correctly, it said in their contract that if they divorced there would be no contact with the children. If I remembered that right then it makes sense that she didn’t since she was operating based on that contract that Noah strictly went by.
It would’ve been nice if she could but she also wouldn’t have been able to truly heal from her pain and recognize her value. That’s just my thoughts lol

Noah's actions toward River were undeniably hurtful and in many ways unforgivable. Still I feel River should have stayed in touch with the children. Regardless of the fact that they were Winter's children they were Rivers children too in every way that mattered. They barely knew Winter while River was their whole world. Losing her left a lasting impact on them and changed them deeply. That's just my perspective.