All the sexmates " someone" had during his marriages never betrayed anyone. It was the "someone" who did ALL the betraying. Why blame them?

Being the other woman / man contains other sins. Tempting people do things that harm themselves and others is wrong.

By your logic drug dealers have done nothing wrong. Is all the responsibility for the negative consequences of drug use on the user and none on the pusher?

Their favourite bullsh*t argument is "If it wasn't me, it would've been someone else." By that logic an assassin does nothing wrong. He can just say, "Well, if I hadn't taken the contract someone else would have. I pulled the trigger, but they killed him. It's just business."