Look at his face in the third gif: he tell Clara that’s too dangerous because he has to, but when she says she will go with him, you can see how much is relieved, because he’ll not deal with one of the more difficult times of his life alone.
“There is a time to live, and a time to sleep. You are an echo, River. Like Clara, like all of us. In the end, my fault, I know. But you should have faded by now.”

