Look at her face, she is both smiling and crying at the same time.
because I think a last kiss with her husband was the last thing she expected. And that’s why I love her so much - she is so happy with the little things she get, so little selfish - think about it - all the companions except for maybe Martha - was almost kicking and screaming for a way back to the Doctor, or had trouble letting him go - but she just seemed so happy seeing him once again, a Doctor that knows, and loves her.
She didn’t blame him for her death didn’t get angry, or tell him to find a way for her to come back, she didn’t ask about him and and Clara - maybe just a bit of jealousy at the conference call, when he wasn’t there.
She just wanted to know why he didn’t say goodbye, and get some closure - a closure they both could handle - nothing more. It’s such a small thing, and he couldn’t even give her that - but she is still never angry or resentful - because she understands why he couldn’t give her that.
When she died in the library she was the was one comforting him, and she dies smiling, telling him that they’ll see each other in the future, and she does the same her. She is so strong that neither death or heartbreak breaks her - she still makes jokes even though she told Rory that the worst day in her life would be the day he didn’t know who she was. in TNOTD she’s dead - but when Clara asked about it she just laughed it of - because I think that’s her way of coping.
A lot of people mistake her for not being emotional - but in reality it’s fits perfectly with her characterization - a vulnerable side she keeps well hidden - she hides her pain, jokes it away - so she smiles at the same time as she is crying.