Thanks for the thread Tati!
Unfortunately I don't think Josh wanted to establish NB as a strong relationship at this point so they were written in a way that kinda made you root for anyone but Nate for Blair, in the EARLIER episodes. However, we did see some flashbacks that alluded to them being happy at some point. Even though insecurites did creep up it showed us a time when NBS was just a bunch of happy campers, and again it made us understand why she decided to put herself out there with him in 10-13. I think she wanted to recapture what she had with him before, like she alluded to when he said he wanted to depend on her more. She said "we'll be better this time." I believe that she did get back with Nate partially because she wanted to, and because Chuck did mess up, so the second time around it was a confusion for Blair as to what to think. But I do know that Nate DID make her happy, unfortunately she could not truly express this because Chuck was blackmailing her. I think Blair needs a break from Nate because I don't think they can work when they have some many problems as a couple.
I do see how people can appreciate NB as a couple for these small moments. I ship LP, which wasn't as popular in season 1 as it is now. My ship was an underdog and I stuck to it and believed and it payed off for me and the fanbase.