The wife should have been consulted. If she had a genuine rape fetish, then there could have been a meeting of sorts, say in two rooms separated by a door? (just thinking out loud) All parties are then aware of the participant's agreement to the action.
In this case the husband is as culpable (I think moreso) than the rapists. I can see that they would have been under the impression that she was into it (and role playing) but their actions do not excuse the crime they committed. They committed a despicable act regardless of what the husband led them to believe.
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