why do friends do this?

I havent spoken to these girls since December and we were really good friends.. They only met my baby once when she was a new born and she is now 9 months. They never made an effort to hangout or be friends anymore. I understand they have their own lives but that kind of "you find out who your real friends are when you have a baby" is real. so they make a group message the other day (those 3 girls are still friends and hangout/talk to each other) with you wanting to hangout so you all agree to go to the movies but one of them can't so instead they start planning to go to the bar next week late at night. knowing your the only one with a baby and husband and your definitely not going to go out for a nights drink? I know some moms do it but many that i know don't do that cus they have a family now. I'm not mad or anything but just wondering if people do this intentionally or what?