Things I Don't Understand

I've noticed a new trend recently amongst my friends.

Blowing things off/flaking out.

Three times in three weeks it has happened to me, with one particular friend. On two occasions he was too tired to go out. I wasn't angry that he was tired. I was angry that once he never called to let me know what was going on.

The other occasion I hadn't invited him along. I had a game group with some other friends and he asked if he could come. I told him he'd have to ask the host of the game group, though I would like for him to come. So after asking, he decided about two minutes before I picked him up that he was too tired to go.

And I had to call him to figure that out! I HAD TO CALL TO FIGURE THAT OUT. I. HAD. TO. CALL. If someone is too tired to go somewhere, I think they know before two minutes before pick up. Like say, a half hour before.

Look, I don't deny that things come up. If someone got sick, that's fine. Please don't come along, rest and relax! If an emergency comes up, go and take care of it! Let me know what I can do to help you!

I don't think say, staying up all night to play DnD when you knew you had plans is an emergency. (This didn't happen to me, another friend.) I don't think that staying up to watch My Little Pony is an emergency. See what I mean here?

Am I weird? Is it common courtesy? What?