It’s probably because for most of the season, it looked like Polo struggled with killing Marina. So, Polo even though he committed murder, is sorry.

He acts like he’s sorry about it. He takes pill to cope. He can’t sleep or concentrate on anything. He’s walking around numb, right? Killing Marina was also a spur of the moment act.

Lu is unsympathetic because of her personality which is harder to forgive because it’s who she is as opposed to what she did. She consistently sucks. The way she hurts people isn’t just a snap, quick reflex. It’s planned and calculated to cause the most damage and humiliation. She ruins people’s lives. She doesn’t care and doesn’t express remorse. She does this wash and repeat, wash and repeat. She’s also very judgmental and arrogant.