I'm not even convinced Ruby would be happy at Oxford if she got a place. Of course, she'd be thrilled initially, but she would still encounter all the problems she's had at Exeter - stress, disordered eating, socialising out of her comfort zone, homesickness, harmful perfectionism. It might be even worse at Oxford because of the tutorial system where you're grilled by academics who can see through waffle. Then there's the 'small fish in big tank' problem. I think Ruby would find it harder to be the best in her subject and the workload would probably be more intense. We've seen how Ruby responds more to praise and good grades than the actual course content, so there'd be less motivation to keep up if she stopped getting the positive feedback.