The reason is sexism.

Either people believe the wives to be innocent because something something men suck women are the best and can do no wrong unlike evil men,

Or

People believe the wives re innocent becausw they think the women too dumb to know what was going on or too disinterested to find out.

Both are sexist bullshit pushed by people who don't understand the rich are all in it together, and are all opposed to being held accountable by the poors