relationship probs...

My boyf and I are having our first year anniversary on Friday and I didn't know it but he took the day off of work to hangout with me all day and make it special. Apparently he told me he would a month ago? I don't remember that though. Anyways I have a previous commitment that day in the morning, a meeting/class for 2 1/2 hours that I can't really skip, I mean I don't want to, it could help my future. So I told him I wouldn't be available until about noon and he got upset and mad at me becuase he feels like I'm brushing him off. I appreciate he's so excited for our year anniversary, but I don't see the big deal in waiting 2 1/2 hours before getting together. Anyways he started pouting and asked if we could just cancel the day😒 after a night of arguing he says he'll hangout that day but he still wants to talk about this later. I don't see what there is to talk about and this has totally never happened before where he gets so dramatic! So I'm confused?! But let me know what you think! Thank ya✌🏼😋