As a Bangel I truly love Sanctuary. Really, I think it is a very important moment for the two of them and I also think they are both justified in their reactions.
For Buffy, it was a very trying and confusing situation. Faith had just wrecked havoc in her life (again) but more than that she intimately violated Buffy and her relationship. God only knows what was going through her mind. Faith slept with Riley and Buffy must have wondered if she had slept with anyone else too. Is there going to be health issues associated with it? STD's, STI's and pregnancy would all be considerations (one I think the show should have spent some time on). On an emotional level Buffy was reeling from the fact that her own boyfriend could not tell her apart from a mentally unstable murder. That really and truly bothered Buffy and I always got the impression that she felt that if had been Angel, he would have known the difference. So imagine her shock and genuine hurt when she walks down those steps and sees Angel comforting Faith? Imagine how deeper it cut when she questions if he knows what she did to her and Angel says he does, and that it isn't important to him. Saving Faith's soul his. Saving her is more important than Buffy. That is such a huge smack in the face. A few months earlier Buffy was his entire existence. Selfishly or not, Buffy must have been devastated.
From Angel's point of view it isn't much better. It is only a couple of months since IWRY and now Faith is telling him that Buffy has a new boyfriend that she is sleeping with. Dagger to the heart much? I can only imagine what it must have been like for him to stand in that apartment with Buffy and have all those memories so fresh in his mind. I think there was definitely a part of him that hoped that despite it all, she would keep her promise and remember what they shared. I can certainly understand him being hurt by her not remembering, as irrational as that was. Away from there relationship though, Angel has made something for himself in L.A. Something that is bigger than him and their relationship and he is reveling in it. This is something that he is good at and he believes in. I can totally understand his stance on the work he was doing and how strongly he defended it.
So, here we have it, the two of them coming together and trying desperately to figure out where they stand with each other now. They get caught in miscommunication and they lash out. Buffy's a fighter, she will always lash out before you can hurt her. It's survival. So they say these horrible, cruel and untruthful things to each other. I can understand that because at the very heart of this episode is two people who love each other dearly, but finding themselves in new and unfamiliar stage of their relationship have no idea who or what to be to each other. It isn't pretty but it is incredibly honest.
