Ok, Ep3S6, Dawn found Buffy where she had died previously and convinced her that it wasn't hell and managed to get her off of that tower that the crazy people built just as it was falling.
Dawn brought Buffy back to the house and Buffy is very nervous, jumping at every noise and in shock trying to rationalize everything that has changed in the house.
Spike walks in and yells at Dawn for leaving him and then finds out that Buffy is alive. He is at first very stunned but by the middle of the episode he yells at the Scoobies saying that magic that deep always has consequenses. The rest of the gang eventually pile into the house and bombard Buffy with questions and Dawn protects her and tells them all to back off. Buffy leaves and goes up into bed.
The Scoobie gang, while bringing her back created another ghost that they cannot seem to kill. It one by one takes over each of the friend's bodies to learn information on how it can stay here... and it finds out all it needs to do is kill Buffy. So it goes the next night to the house to do so. Willow and Tara conjure a spell to make the ghost take on a physical form and Buffy kills it first.
She then goes to the Magic Box to thank her friends for getting her out of "hell"... and then goes outside and tells Spike that they pulled her out of "heaven" and that she is miserable. She confides in him that she was happy and at peace... she knew that her friends and Dawn were all OK. Time meant nothing... nothing had form, but she was still her. She was warm, and loved and finished, complete. Now she's not. She was torn out of there, pulled out by her friends. Everything here is hard, bright and violent, everything she feels, touches, this is hell. Just trying to get through days knowing what she has lost.
Then she tells him that they can never know... Never.
(The last paragraph I was listening to the ending of the show when I typed it to make sure it was right. hehe)
Enjoy.