system
Given the following post, respond as if you're commenting on Reddit:
human
CMV: I don't believe it's immoral to sleep with someone who is married.

I used the search and found one similar post from 4 years ago without much conversation (and also taking the opposite stance), so I figure there's plenty more room for discussion on this topic. 

Assuming the marriage between A and B is closed and monogamous, if B decides to cheat on A by sleeping with C, then even if C is fully aware of the situation, I do not believe C is doing anything immoral.  

Reasons:  

1) The immoral part of cheating is based on breaking a commitment. B has obviously made a commitment to A, and B is in the wrong for breaking that commitment, but C has not made any obligation to A and thus is not contributing to the immoral act of cheating.  

2) Even if C's actions indirectly end up hurting A, the cause from that hurt ultimately stems from B's failure to remain faithful. C did not cause that pain. A really bad analogy could be that B promised A that B would buy cookies for A, but then C goes to the store and buys all the cookies that are available, leaving none for A/B. Now, A is hurt because B could not keep their promise of cookies for A, and C is the reason that B could not keep that promise, but C did not do anything wrong, even if C knew that A and B wanted cookies. C is not being nice by not giving them the ability to get cookied, but not being nice is not immoral, and ultimately A's hurt is caused by B not being able to keep B's promises.  

There's probably more to mention but I'll stop leading the convo here and see where it goes. Very excited to hear some counter points!


Edit - for latecomers to the thread, interested to hear your thoughts on if C was a prostitute paid for by B. Morality of prostitution aside, is C expected to give up their source of income and refuse married customers?
gpt
I personally see this debate similar to being an accessory to a crime. Imagine B wants to steal money from the bank that A owns. If C actively helps B plan the heist was C acting immorally? Or if C knowingly was the get away driver were they acting immorally? All C did was theorize how to steal or just drove a car. To me it's immoral because they fully know how their actions are going to be utilized to hurt someone.

On the flip side, if B steals money from A and hails a cabby outside, the cabby isn't acting immorally if they are unaware that their ride is helping a criminal.