This is for real - I experienced it years ago with my ex-wife. It was the other way around though - when we met she wasn't on the pill and we got along fine. She went on the pill and went nuts not long after, but I didn't connect the two things at the time.
I later read about this somewhere else (similar study); the researchers there hypothosised that when women go on the pill it effectively tells their body that they're already pregnant. This in turns leads them to seek out people who are genetically similar (most notably family), probably because they are most likely to protect the woman and her 'unborn' child.
