I thought River and the Doctor’s timelines were going in the opposite direction. We saw an episode where the Doctor saw Mel regenerate into River, and she didn’t know who he was really. So WHY was she in this last episode and she knew him and knew they were married and everything? I am so confused. Did the writers forget about the timeline business?

Edit: Okay, so if their timelines are just out of sync and it is random each time they meet, why do they bother syncing their diaries? Even if they did find where in the diary they are, it still doesn’t tell them what they have or haven’t done together. (but it does make sense if their timelines are going in opposite directions) I do remember the Doctor mentioning that what is in her diary is his future so he won’t look at it (and vice versa for her). In The impossible astronaut River told Rory that they were meeting in reverse order and she feared a day when she met the Doctor that didn’t know her. So I don’t think their meetings are just out of whack or random.

When we first met River in an episode with Tennant he didn’t know her and she knew that was the last time she would see him, which is why she accepted her death right then. It was a very powerful episode because of the opposite timelines and if you take that away and say that it’s just random out of order meetings then the moment she died was less meaningful and just disappointing.