If the pay for singles wasn't close to twice the pay for couples (I get $320 partnered, I'd get $600 single) I think a lot less people would be fudging their relationship status, but I can't see the powers that be changing the legislation any time soon even though it would save a fortune on fraud investigation. I remember it being a huge shock to the system how much less I got paid when I moved in with my current partner.
It all depends on your partners income too. If your partner was on the dole you'd get more than if your partner was earning $1000 a week.