Disgusting

Am I the only one that thinks it's disgusting when a man (or woman) can put they're new gf/bf completely before their own child ALL THE TIME. I'm currently going through this with my ex, ever since he started dating this girl 5 months ago he's put her before our son. He doesn't even see our child or buy him anything (like diapers) anymore at all. It just disgusts me. And it also disgusts me how she thinks it's perfectly okay that he does nothing for his child and I honestly think it makes her look just as bad as he does.