C/B <3

“Nate! How could you?” she cried, “How could you!?... Y-You cheated on me, w-with h-her of all people!” tears started to fall from her eyes and they started cascading down her face. Nate stood in the middle of the Archibald library, camisa and tie missing, bending down to pick up his discarded items of clothing he said carefully and slowly. “I’m sorry Blair, you said you wanted to wait, and there has been so many things going on lately at home. And after things ended last night I thought we had broken up” Nate looked over at an uncomfortable Vanessa who is frantically trying to...

Chuck & Blair have been through pretty much everything and it isn't abou to get better.

Season 2 Episode 19- "The Grandfather"
As many have seen the 11 segundos long video of Blair & Chuck were Blair says "Take Me Now" it doesn't end well after Blair finally realises that Yale isn't going to happen she goes bad. During what I believe to be a party but it might not be Blair & Chuck kiss but Chuck asks Blair for her old self back and she refuses after this Nate checks up on her and Blair holds his hand and asks him not to leave. This I think is how the Nate & Blair situation begins....