How do they treat their co-parent?
In addition to examining how a person treats their children, consider how they deal with and speak about their children’s other parent? Do they only treat them with hostility and anger? Is your partner one who only has negative things to say about their co-parent? Are they hypercritical of their co-parent without ever stepping in or stepping up to help? Remember that you are only getting one side of the story and there’s an entirely different side of the coin to be considered.