Why would adultery make someone deserving of death? Adultery is not equivalent to murder... or even rape.
It is more a form of dishonesty and breech of contract.
It breaks up relationships and it causes suffering... but nothing so great as death or loss of self-autonomy.

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"Man lives in the sunlit world of that which he believes to be reality. But unseen by most is an underworld, a place that is just as real... but not as brightly lit... A DARK SIDE!"
-opening from Tales From the Darkside