Learning can be like that. When it gets hard, it'd be much easier to give up. And lots of learners do. They don't like learning when it's tough - it's hard work, they expect to learn easily and if they don't they might think it means they're no good. Or they might blame the subject or the teacher. Or they might just get in a mood about it.
Try reciting the alphabet backwards without a pause. What happens? How do you feel when it goes wrong? Are you going to give up? It's just silly isn't it? It's not worth bothering with. What a waste of time. I don't know why I even started in the first place... Just some of the things that happen when learning gets tough.
You will be in this situation many times during your education. How could you cope learning when it gets tough? Watch Andy Murray's last game and think about how he overcame a difficult situation.