Responses
I think it's obvious. He took him for granted and didn't consider his feelings and needs
I think it’s pretty clear that it wasn’t some big incident that made them break up. It was More like the The last straw. It’s pretty clear that Leo is really selfish and never took into consideration how JJ might feel About him acting, however, he pleased
I hope those flashbacks clear what Leo did so wrong , to the point of JJ breaking up with him.
So far I see Leo really loves him , but he could be that kind of childish boyfriend , and basically JJ is like his reason to give all in the racing and now that is gone. Let's hope he don't end up in a hospital from some accident either in a race or faint from not eating , because of it too.