Rupert spends his entire flight to America trying to work out what he'll say to Buffy when he arrives in Sunnydale.
It's taken everything in him not to phone her every single day to check in and make sure that she's doing alright, that both she and Dawn are safe. He told himself that he'd call if she called first… knowing full well that she would be too afraid to reach out to him after the way he left.
But of course, he couldn't call her because—
Well. If he spoke with Buffy and got even the vaguest sense that something was wrong, he would have raced back to her. He had convinced himself thoroughly that his departure had done her good, and returning at the first sign of trouble would have done one of two things: proven him wrong, or reversed her progress.
Even so, it was a mistake, leaving her the way he did. If they had parted on better terms, she might not have felt completely cut off from him. Maybe things back in Sunnydale wouldn't have gotten so bad.
Now he's genuinely terrified that she won't want him there. Very little would wound Rupert as deeply as it would if he came back into her life and Buffy no longer felt like he was of any use to her.
His fears are temporarily forgotten when he bursts into the Magic Box to see Buffy and Anya facing off against Willow. So it is her. He finds that he's not surprised, though he wishes he were.
Immediately, Rupert is single-minded, working to incapacitate Willow above everything else.
It feels like a victory of sorts when she doesn't question his presence, doesn't tell him to go back to England and leave the fighting to her. He even dares to think that she might feel relieved.
Rupert looks over to her, really looks for the first time he's arrived, and out of everything that could come out of his mouth it's:
"You cut your hair."
He points it out because it's easier than spewing the endless apologies that are on the tip of his tongue, or articulating just how much he's missed her.
For a fraction of a second, Buffy doesn't seem to know how to react.
They let their guard down simultaneously and fall into a hug. Everything is easy, if only in that moment as they hold one another.