I just finished watching this scene for the 4th time and I don’t remember how sad it was. This scene really showed Chuck was finally at his last stage of grief, acceptance. How he set his feelings aside for the benefit of Blair. The part where he said something like “I left the empire building 2 min after you didn’t show up, but Louis stayed all night”. But then they slept together while Louis was waiting. I felt really bad for Louis(he did not deserve that)In Chucks mind he probably thought that this was the last time they’d be together since she was going to get married. He let his guard down because he finally realized Louis would take good care of her. I think knowing how it feels to let someone you love go and how much it hurts is the reason why I find this scene so sad😢😢😂