At 12 they separated and when they are 19 is when they meet again, they split because like friends you sometimes find new ones and forget about the old.
These don't seem like very high stakes. Not that the stakes always have to be high. But in the first post, you posed the question whether they could re-establish their friendships or if they were meant to not be friends. If they just drifted ways at the tender ate of 12, why would it be that difficult for them to become friends again at 19? Or in the alternative, why do we care if they become friends again? Unless there's more to why they stopped being friends -- somebody did something to somebody else, and that something needs to be corrected/apologized for.