Margaret
Oh, it was Henry's sister! She'd seen pictures of her in the books she'd read, and she was beautiful, just like she'd thought. After seeing that Anne Boleyn had wanted to talk to her boyfriend and not her, Gabriella hoped that maybe she could talk to his sister.
A PRINCESS!
Plus, she couldn't hate Gabriella, right? She wasn't one of the ex-wives. But, she saw that Princess Margaret had decided to talk to Henry alone, so Gabriella waved shyly at her, and waited off to the side. Maybe she'd want to talk to her later?