By this standard, every spouse that cheats is motivated to kill and I don't buy that.
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You just called it a standard I didn't.. Your statement that this is a standard is illogical. His own motivation in fact is just that- His. In my mind it points strongly to HIS culpability...
It is anything but illogical. If I remember my college logic class, here is how I would map your argument.
(A)A person cheats on their spouse.
(B)The person's spouse turns up dead.
(C)Therefore that person must have killed her.
A + B does not necessarily = C
And I don't see what is illogical about a statement that says cheating on one's spouse is not an uncommon occurance and that everyone that cheats on their spouse should not automatically be assumed to be a murderer.