I’m Ready For The Punches
Cheating is always a product of conscious choice. You don’t cheat by mistake because you have to make a conscious decision about whether it’s worth it to pursue someone even if you’re currently in a relationship with someone else. As Newton’s third law of motion stated, for every action, there is an equal and opposite reaction. Just be ready with the repercussions.
This guy must have ended in good terms with his ex since she allowed him to live with her. He became her roommate, together with the girlfriend’s new boyfriend. They hooked up several times, but he was ridden with guilt when the guy started to befriend him. Now, he is planning to admit everything to the guy face to face.