In an ideal world adults would be sensible moral people. But sadly, I think when a marriage sours the children can be a reminder of that partner or worsen the feeling of failure. A weak minded person can easily take that pain out on the kids.I don't want to make a thread on this, but this is just a spin-off. I wonder if the love you have for their mother affects the love you have for your children? Say you're married to woman you're genuinely in love with. Just have a deep, persistent affection towards her - would it be easier to love and care for the children you have with her? Alternatively a marriage of convenience where two individuals marry each other my they simply meet each other's criteria in looks, income, status etc.
I know the rational and PC answer would be to separate the two, but surely there is some emotional spillover because your children are inextricably linked. They're the literal manifestation of your connection.
Hooyo’s do this too, probably more than the dads. Dads just leave. But hell hath no fury like a woman scorned.