You said you’d go. At the time, you meant it.
But now the day is here, and you don’t want to anymore.
Nothing happened. Nobody upset you. You haven’t suddenly become busy.
You just changed your mind.
You pick up your phone to send a message. Then you stop.
You need a reason.
Being tired might work. You could say you aren’t feeling well. Maybe something came up.
You stare at the screen.
The truth is simpler than any of those.
You don’t want to go anymore.
Somehow, that doesn’t feel like enough.