I'm actually writing a fic right now that daels a bit with post-GITF Rose and might delve into that a little. I think the real answer is a mix of the fact that a) meeting Sarah Jane forced her to sort of come to terms with being 'the latest in a long line', b) she didn't actually SEE him do anything wth Reinette and c) Moffat is not fantastic at character continuity.

I WONDER THAT TOO LOL. In Father's Day she implies they're broken up, but I have to wonder if it was one of those things where she clearly sees the relationship as over and he not-so-clearly... doesn't.