Oprosik

In general, this wouldn't even be a full-fledged murder, but rather a vigilante act.

:) Vigilante justice is when you introduce an ancient (not even medieval) "stoning," which no reasonably adequate society would accept. And if you don't introduce it, then it's a crime (both morally and legally).

Not for any reason, but in the case of infidelity.

=for any reason

Besides, if you really want to settle everything this way, you don't even need to go to court.

They'll enter a "state of affect" and file a lawsuit. And then they'll cry for the rest of their lives.

After learning about the infidelity, it's easy to enter a state of affect, when self-control is no better than that of a drunkard. But in this case, there is no guilt on the part of the person who entered such a state, but the drunkard is to blame himself, he needs to know his limits.

If you judge it that way, then most murders are committed in a state of affect, one way or another. "I had no money, everyone cheated and ruined me, I fell into depression and robbed," "He looked at me sideways, I got scared, my natural self-defense mechanisms kicked in and I killed" and so on. Raskolnikov was also in a state of affect when he killed the old woman's relative. And he didn't just kill the old woman for no reason, but under the influence of external circumstances, poverty, high interest rates, etc. So, he wasn't to blame then, right? If the old woman had given a lower interest rate, he wouldn't have killed her, right? That's how we end up with an absurdity...