The problem came down to me not realizing how long he was going to disappear for, him not thinking about the fact that we'd planned to go to breakfast so I would put off eating which in turn caused my sugar to remain low until I finally gave in and ate breakfast without him, and that I've been feeling rejected in other aspects of my life (inability to get a job, difficulty of making friends in a new place, etc) so this feeling of rejection was kind of the final straw.
I didn't realize it would take as long as it did, so I didn't think about setting a time limit. Now I know.
Normally, Keith is the sweetest, most considerate guy. Half the time I barely have to lift a finger when we're just hanging out. However, he consistently forgets that I have health issues that require me to stay on a schedule. I eat 2 meals a day and 3 snacks to keep my blood sugar regular. My breakfast meal is at the same time every day. Normally we don't eat it together, because he sleeps later than I do. Since we'd stayed up all night, he was going to take me out for breakfast, but as soon as he got into his own space - my needs went out the window. Like usual. So, instead of making sure he was done in 45 minutes so we could still go to breakfast without it being too late, he was gone for an hour and half while I continued to put off eating because we were supposed to eat together, my sugar crashed, I went into a hypoglycemic rage, and now we're still dealing with the fallout.
Sure, he shouldn't have to be a mind reader, but is it so much to ask that he remember something as important as my health and how him pushing back our plans affects how I feel physically as well as mentally? I don't think so.
We both made mistakes - mine was convincing myself he's capable of something he's not and his was not thinking things through with a clear mind.