It would have been easier if he had never come back. And how strange it is, Willow thinks, that she reacted that way, when a few months ago she would have given anything to see Oz return.
He was her first love. He still means so much to her, and he always will. More than that: he'll always be a part of her, and she hopes one day to see him again, when things are less… raw. Nothing can change that.
But what she had with Oz is her past now, and that is unchangeable too. Tara is her future.