One of the points you have to bring up is intent. Is the older person having sex with them because they love each other, or because the older person is using the younger? Or is the younger person using the older? With the pedo-ring, it was an obvious older-abusing-younger, with maybe a few younger-using-older. Kind of a co-using, it the wacky sense people can make. While Steve and Wulf loved each other, are were expressing it with sex.
I'm kinda biased, since I have a pair of friends that fell in love when one was 29 and the other was 17. It's been a couple of years, and they're now happily married with a two year old. As far as I know, sex didn't start till after she was 18 (which doesn't matter in this state, since they weren't married at the time and you have to be married to have sex here. Oh, and it has to be missionary style sex too.) but they're a couple that work.