Young man had suspected his wife of infidelity for some time. He decided to set a trap for her, telling her he would be out of town, but instead he lay in wait together with his friends. His fears were confirmed when he caught the two of them in the act of penetration. In that moment, he lost control and brutally beat the side dude.
Although such a reaction may be understandable to many people, it is by no means justifiable. Two consenting adults can have voluntary sex regardless of marriage in most civilized countries of the world. This is not a reason to physically harm someone.
