(River kisses the Doctor.)

DOCTOR: Right. Okay. Interesting.

RIVER: What's wrong? You're acting like we've never done that before.

DOCTOR: We haven't.

RIVER: We haven't?

DOCTOR: Oh, look at the time. Must be off. But it was very nice. It was, it was good. It was er, unexpected. You know what they say. There's a first time for everything.

(The Doctor goes into the TARDIS.)

RIVER: And a last time.