8. He Wasn't Going To Turn To The Dark Side Just To Save Padmé
As we've shown before, George Lucas had a pretty good idea of where his prequel films would go way back when the original films were released. As he wrapped up Return Of The Jedi, his mind fell back to the notion of showing Vader's origins. About this time he came up with the broad strokes of the prequel's narrative - Palpatine's political rise to power and Anakin's fall to the dark side and eventual dip in a lava pool - setting in motion films that wouldn't emerge for another decade.
The original plan for Anakin's fall was going to be him turning against the Jedi, slowly cutting them down unbeknownst to his (very public) wife, with Obi-Wan solving the mystery. That's similar to what was eventually delivered in Revenge Of The Sith with one major difference; in the finished product the motivation has a lot more to do with Padmé.
That's because up until the eleventh hour the story had always about how Anakin became disenfranchised with his own order which seems a lot more believable than moaning over his girlfriend. Lucas, for some crazy reason, decided on a shift in focus, but not until after principal shooting of Episode III, meaning the importance on Padmé's death had to be greatly expanded upon in reshoots done at the last minute. That's why those romance scenes feel a bit forced.