That would make me angry. Perhaps he would benefit from an appointment reminder on his phone or checking his planner every morning. Or scrawling it on a petroglyph.

Either way I am sorry that he disappointed you. Your feeling this way is completely understandable and you should express to him how it really made you feel, because, even though you don't want him feeling overly contrite, communicating how much hurt it caused will prevent resentment from building up in the future and possibly even strengthen your rapport when he validates you (and he will if he's worth his salt).