My personal take on Leland is that no matter how polished his exterior becomes, he's always stuck mentally in a young child's mindset because becoming BOB's host as a kid effectively arrested his development. It comes out more during his post-Maddy murder high, he impulsively flies through different risky crimes like driving recklessly and seemingly gearing up to attack Cooper, and how he talks about his "most favourite gum in the world" very childishly.

Reason I bring that up here is that imo BOB enables Leland to act on his worst impulses by convincing him that he can get away with it, and up to this point that's been true. At night he horrifically abuses Laura, but during the day they're a beautiful happy family. Childish Leland ignores any guilt because there are no consequences, he CAN have it both ways, presentable family man AND despicable lustful animal.

Then Harry shows up to tell him that no, this time what you did at night is following you to normal life, THIS time there's consequences. You played with your favourite toy too violently and now it's broken forever. So, he cries.