It's one of those things where you know you fucked up but no matter how bad you feel about it or how badly you want to confess and apologize, you just can't because it will completely ruin you're life. So you sit there forced to lie and feel like total shit about it, knowing you deserve to be exposed for the piece of shit you are, but still hold onto that shred of hope that maybe some god out there might forgive you and grant you a second chance where no one finds out, you learn from your mistake, vow to never do anything shitty like that again and try to just keep on living a normal life.

That or maybe he's just a sociopath who feels no empathy or guilt