Anakin killed Padme
I don't know if this is old news or not but in the scene where he's getting the Vader suit you can hear the ekg stop for a second or so. He dies. But then comes back. In that second it's possible he's reaching out to Padme, drains her life and as the emperor said, in his anger he killed her.
Or you can go with the explanation that she "lost the will to live"