Argue about it being a one time thing

From Create Your Own Story

"Maybe there's a reason this happened. Maybe it doesn't have to be a one time thing," you suggest.

She turns back to look at you with disgust. It seems to be mostly with herself. "No, it's a one time thing. It was a mistake and I already feel horrible about it."

• settle on that. no reason for this to get worse than it is.
• press the issue a little further. there's a reason she cheated.