@puroandson @doctordani @bluesqueakpip
Thank you for your answers, although I must say I can only agree with @doctordani.
I don’t think the moment was supposed to be kept intimate, I think it was something more complicated.
Like, imagine River was alive when the Doctor had to go to Trenzalore, that would explain why River was sorry. She was sorry because the Doctor was forced to open his grave, revealing one of his secrets.