What event does Edgar’s banishment of Heathcliff from Thrushcross Grange remind Catherine?

Heathcliff's banishment reminds Catherine of the way Heathcliff was treated as a child. It reminds her of the fight between Heathcliff and her brother.... their first separation.

I was a child; my father was just buried, and my misery arose from the separation that Hindley had ordered between me and Heathcliff. I was laid alone, for the first time; and, rousing from a dismal doze after a night of weeping, I lifted my hand to push the panels aside: it struck the table-top! I swept it along the carpet, and then memory burst in: my late anguish was swallowed in a paroxysm of despair. I cannot say why I felt so wildly wretched: it must have been temporary derangement; for there is scarcely cause.