Often single moms neglect the children they have with their ex, when they find a new partner or when they are partying and searching a new partner.

Is this considered to be common behaviour? Can this be seen as a consequence of hypergamy?

Has this something to do with the fact that when they cut bonds with their ex, they somehow also cut bonds with their children?

In principle, parents should care and love what is their own genetics moving towards the future. Might lack of love and respect for the (demonized) ex be a reason why some single moms act so particularly careless against their own children? I don't mean only bad (stupid) parenting, but particularly neglect.

Might it be that women tend to consider their children without value if they consider the father to be without value?