Why the sudden change of plans, Ma Jolie?

Earlston, Scotland, 02:50;

Xi Yuan was a light sleeper. It wasn't possible for the girl to slip out of the room without disrupting his slumber, and she was aware of it. So that night, she insisted on pulling an all-nighter with the book she'd been reading. The man didn't refuse her request straight away, since she'd slept for about three hours that noon. He, as usual, just offered to accompany her. But she'd turned him down, prompting him to get some rest as he'd been working and attending meetings all day long. 

'You need to understand that your health is no less a matter of concern to me, Yuan', she'd told him, 'And since my ease of mind is necessary for the recovery, go to bed.' Left with no counter-argument, Xi Yuan had to give in to her demand.