[ She's emotional, more than anything else; and her standard procedure of dealing with unnecessary emotions is to hold them in until she's able to be alone. But she's not alone here, and she trusts him especially after what he said to her.
[ She can understand why he breaks contact after a while, but it restores the awkward silence between them and the room feels a lot colder without his warmth. Yet she doesn't know what to say, so she keeps the silence, unable to look ar him straight.
There's probably a lot she could have said, but words aren't coherent right now and maybe it's best to stay quiet. ]
[ After a while she lets go, but only to retrieve her own book to read. Since she needs both hands to organize her notes, she'll compensate for that by leaning against him a little.