am I being stupid?

Okay so on the 30th is my 1 year with my boyfriend. We have forever had these plans that on the 29th he's saying at mine. And then I'm the 30th I stay at his and then on the 1st we watch the grand final for AFL football and I may say again depending on if I'm working. 
He even reassured me yesterday that I know the plan and I'm okay with it. Then tonight says "hey babe grandfinal day I'm with the boys sorry" 
I am pissed off about it. Like I didn't start a fight, I just let it go but ugh we had these plans and he's ditching me for the boys? 
Am I being stupid? Or would you be pissed too? 
Because it means I can't stay at his the 30th (the day of our 1 year!) when we are going out during the day and then out for dinner and stuff at night.