Though she's aware of Pel's daily visits, Sina tends to pretend she's asleep until her friend goes away again. It's not that she's angry with her, or even that she doesn't want to see her: but Pel is a reminder that it was real. It can't be written off as a nightmare or a vision when another witness-- and victim-- is here in the room with her, and not as ruined.
So Sina lies on her side, back to Pel, praying she can live in denial just a bit longer.