"My friend is planning to cheat on his future partner to see if he feels guilt over cheating. What should I do?"

My friend (18M) has recently announced to our friend group that he is planning on entering a relationship with a co-worker (18F) and plans to cheat as soon as possible. The only reason he wants to do this "experiment" is to see if he can feel guilt over cheating. He's been acting on this plan for months to form a deep connection with her beforehand to "deepen the blow."

Doing so, he discovered her current mental instability and her recent acts of self-harm. We expressed we didn't support him and asked him what will happen when she finds out. He doesn't care if he gets caught or any of the consequences that may happen to his mentally unstable co-worker if he does get caught.

I asked him about the situation again to see if he changed his mind about it and he said he is going to commit to the plan. He even brought up a weird Overwatch comparison and said that Moira did unethical experiments on Reaper for the betterment. For reference, Reaper states that he now lives in constant pain because of her weird ass experiments.

Regardless, he does admit what he is doing is wrong but still wants to do it. In general, it's just this whole situation is uncomfortable and gives me a sh!tty feeling. It was only made worse when he started making jokes about her offing herself. I don't know what to do and am unsure how to go about the situation.

What do you think he should do? This is what top commenters had to say:

mzpljc said:

Dollars to donuts this guy commits some heinous crime in the future, to see how it feels.

[deleted] said:

dear god please tell his coworker what he’s planning and cut him off. he’s clearly a bad person. if you have texts from him about this, take screenshots and send them to her via instagram or something. she does not deserve to be hurt for the sake of his twisted experiment, and you shouldn’t be friends with someone so eager to do something so overtly cruel

Conscious-Fill5562 said:

Guy seems like a sociopath should probably not be friends with him

skeeballbob37 said:

you need better friends, you are going to be judged by the world for keeping company with someone like him.

He later shared this update:

My friend found the post before I took action and read all of your comments. He texted me in the morning asking about it and I confirmed that it was about him. He told me that the post, the comments and our friend group discouraging him made him regret his plans and anything he has done with her to help further it.

The only problem is that although he doesn't want to do the experiment, he still wants to be with her for a short time specifically for sex. I told him there is no point in hanging around with her anymore and to disconnect himself from her.

He resisted to the idea but eventually agreed to it and asked to stay in our friend group. We as a group refused and decided to cut him off. We told his co-worker about the situation and advised her to tell HR and to move on from him.

We also told her that if she needed evidence against him to contact us and welcomed her into our group if she wanted to join us. Thank you all for your advice and for all of your comments that changed my ex-friend's mind. If there is anything I should consider before moving on, please tell me.