I'm angry because he ate without me.
Did he save you any food?
He ate my food and he said he didn't.
Conflicting schedules sometimes happen and we can't always do things with each other. If he ate your food and lied about it, you have the right to be upset.
It's not fair. All I want to do is share my food with him but he doesn't understand.
That's fair, you're upset because your SO doesn't listen to what you want.