After the Obi-Wan/Anakin duel, notice R2 kind of automatically follows Obi-Wan onto Padme's ship? R2-D2 seems to sense Anakin's turn as well, for example he says something to Threepio to which Threepio answers "Well he is under a lot of stress". And when Anakin asks him to stay with the ship on Mustafar he gives a concerned whir as if to say something has changed. So I get the feeling R2, rather than wait for Anakin, has practically abandoned Anakin as if he has written him off. It's like he no longer has that bond that would make him wait. What do you think?