You tell your good friend, “Let's catch up later”. You assume you will see each other at the gym, where you both usually go to work out in the evening. You don’t see him at the gym, and later you...

You tell your good friend, “Let's catch up later”.  You assume you will see each other at the gym, where you both usually go to work out in the evening.  You don’t see him at the gym, and later you receive an angry text asking, “Where are you?  I thought we were getting together tonight?”  What is the most likely source of this conflict?