The novel Beloved is a complicated story about an escaped slave and the trauma she suffered over how her children were treated and what she ended up having to do to them to avoid a return to slavery.
In the historical context of the story, we have to remember that slaves were legally property, whether they had escaped or not. Slave marriages had no legal status, and all the children produced by such marriages were owned as property as well. This meant that your spouse or your kids could, and probably would, be sold away from you at some point.
So it was common to see much less of a bond develop between slave mothers and children in those days, because heartbreak, trauma and in the case of Beloved, insanity could easily result.