How much does River Song know about her own death?

Question

At the end of the episode "The Husbands of River Song", River and the Doctor are on a date, at the Singing Towers of Derillium. The way River is acting, she seems to be aware that

she is nearing the end of her life, as her diary is almost full and The Doctor has kept putting off this date for a long time.

When she realizes the date will last for a while, she relaxes and start enjoying it.

To me, it seems obvious that River understands where she is in her timeline and what it means to be on this date:

That the next time she sees The Doctor will be when she dies.

But in "Silence in the Library", when she meets The Doctor for his first/her last time, she doesn't appear to have any idea what's about to happen until the very end.

Am I right in thinking Moffat has played around with the back end of River's life to fit this year's Christmas special?

Answer 1

When River meets The Doctor in "Silence in the Library", we now know that she is almost certainly aware that she's going to die soon. The Doctor has basically told her that in his future/her past.

However, there are two key reasons why she might not act like she knows her own fate:

• She's very good at keeping secrets from The Doctor about his own future. She knows that if he realizes too early what's about to happen, he will try to change it, possibly risking his own life in the process. From River's perspective, it's of paramount importance that The Doctor survive, because otherwise all of her time with him will never have happened. So, she puts on a brave face right up until the end.

• She may, in the back of her mind, still hold out hope that he will fix things. She must be aware by now of how he "saved" Gallifrey, and she has seen him do the impossible many times. Clara makes almost exactly this point in "Face the Raven" -- that The Doctor always somehow manages to make things right in the end. River may have hoped that if she kept her options open, he (or she) would figure out some way to keep her alive.

Answer 2

At the time of Silence in the Library we can infer that River knows she is nearing the end of her life. She refers to the Doctor as the sort of man who knows exactly how long of a diary you are going to need.

She has a general sense that it's coming to a close, but knows nothing.