If you cheat on your wife, which implies you had an extramarital relationship without her knowledge and without her consent... obviously you have deceived her and this is represents harm whether anyone in the world ever finds out.
You seem to be going out of your way to misinterpret what I said.
People who are against weighing harm and suffering typically argue for the "moral authority" angle, whereby some entity (usually God) declares things wrong just because he says so. Sin, for instance, is the idea that some things are wrong even if no one is harmed by them, just because God doesn't like them.
That's what I'm contrasting against.
Your characterization of me as someone who selfishly ignores "indirect repercussions" (whatever you mean by that) is not accurate. Any negative repercussion represents harm in my view of morality, whether the party is aware of it or not.