One thing I've noticed is the number of witnesses who have affairs seems to be higher than among the general population. I just don't know any worldly marriages that have ended because of affairs - yet I know not a few JW's whose marriages have and have heard about many more. One woman I know married three times and each time it ended because of affairs (I don't even include 'technical' affairs, admitted to so that couples can divorce, in these numbers).
I've heard it said it's because of the youth of JWs when they get married. Yet I've known groups who marry young too, such as in the large Indian community I grew up with. Again affairs seem rare. Perhaps it's because Witnesses have to admit to it that we get to hear about it?