The way he reacts to what she says makes it clear that he's not at all comfortable and guilt hits her for letting him see her like this and giving him the illusion that he has to stay and keep her company while her body degenerates further into itself. As he takes her hand, she attempts a smile but, like everything else, it doesn't come across quite right.

"I hope." She nods both with and without purpose and reason and tries again. "I hope you're right."

It's a lame attempt at giving him the recognition he deserves for the smile he's attempted and the knowledge he's imparted - something about mortality being flexible? - and she makes a mental note to ask later, if she can. If he's right. And, because she feels like it's necessary to ease his conscience, she tries to tell him he doesn't have to stay. The words don't all make it out, but she tries. She even lays her other hand on top of the ones they've rested on his knee.

She's trying to be encouraging. It's what she does.