Of all the photographs taken of him at his wedding, there was one that John and his friends sharply disagreed about.
Given that ...
all John's friends said this picture doesn't really resemble him,
How can we explain that ...
John thinks it's the only picture of him that does resemble him?
Evaluate / Goal
In order for John and his friends to be so sharply divided about this photo, the answer will have to tell us something about the photo that would distinguish how his friends see it vs. how he sees it.
Maybe John is an ugly dude but doesn't know it, so the one photo that makes him look handsome looks "right" to him but looks wrong to all his friends.