How do they handle the aftermath?

Let’s say you live the guy/girl, and it’s been some time and you’re talking again. Have they addressed what happened? If you honestly believed they were at fault, were they capable of saying anything, let alone “I’m sorry”? I dated one guy who lied huge, unmistakable lies. He not only completely disrespected me, but tried to tell me I was harsh to him when I discovered his huge, obscene lie. Balls. It’s possible to move on with someone who makes a mistake, but how do they handle the aftermath?