Based on a true story; only it was between a guy and girl.
One night Autumn and her somewhat new girlfriend Cindy were fooling around in bed, discussing their turn ons and kinks. After teasing and testing Cindy a bit to see how receptive she'd be, Autumn brings up that she enjoys diapers. And she enjoys seeing others in diapers too. She's also wearing one right now!
To Autumns relief, Cindy is very accepting. She even wants to try one on and wet it. A couple wettings later, a diaper change here and there and next thing you know you have two girls making out in diapers.
BTW, this is how we got together. Shane told me in a very similar way.