I’m glad you mentioned the particular issue you’re having. It sounds like he forgot you were waiting for a call back or else didn’t realize you needed a call back. If you were clear and he forgot your call back, then it’s hard to blame him for something he honestly mistook. In that case, you’re going to have to make the second call to get what you need from him, knowing he’s forgetful. Some people are.
However, if he’s purposefully ignoring your call back, then understand that he doesn’t want to be the guy you get to vent to about external events — whatever they are. Rather than try and make him be someone he isn’t, look to another friend to be your person you vent to about these situations.
You’ll be a lot happier if you don’t expect things from him that he can’t (or consistently won’t) give you.