sometimes people don’t understand that someone can be busy with things out of their control and it’s not their fault for being unable to be at your beck and call 24/7
The least they could do is acknowledge that the other person has their own needs and problems and understand that they aren’t able to keep promises if something out of their control pops up and not immediately deem them as uncaring if they don’t reply to you immediately
they’re people, not personal friend robots that you throw away when you think they don’t work anymore