There doesn't appear to be anything illegal in the revelations on TV last night by the spurned girlfriend. If the 'allegations' are true, they contain little more than suggestions of some minor inappropriateness. And nothing that wold lead us to question Rann's capacity or suitability to be Premier.
Why then is it so interesting? Why is the woman's story worth a lot of money?
Part of it I guess is our growing obsession, as a society, with the private behaviours of famous people and part of it is the fact that Rann has initially denied it (since Watergate the big story has always been the coverup).
But beyond that I think that there is a growing puritanism (the new puritanism?) which endorses the idea that our private behaviours are appropriate matters for public examination and intervention. We see this in regular moral panics about teenagers and alcohol, when government statistics suggest that dangerous drinking by teenagers has been stable or falling over recent years and that the behaviours of their parents are more of a worry. The story with road safety follows similar patterns. We also see it in the 'obesity epidemic' and a desire to blame it all on fast foods etc.
Often this new puritanism is justified on the grounds of cost i.e. obesity costs billions, excessive alcohol consumption costs billions. But this obviously doesn't apply in Rann's case.
Another reason might be that our media, presumably reflecting the public, finds it far easier to cover politics as if it was, as someone said, politics showbiz for ugly people. An affair is easy to report and to consume. Far easier than, say, the workings of an ETS.
We've seen a lot more of this 'politics as amusing soap opera' stuff in recent years. This type of coverage used to be clearly separated and labeled as comedy. But just as commentary has been allowed to leach into reportage, so too has the ironic, satirical and prurient been allowed to get mixed up with reportage and analysis.