From Season 6 Buffy was brought back to life によって her own フレンズ from "Heaven". She was feeling that she wasn't there but feeling very ロスト in reality. Somehow effected her feelings against her enemies. Like for example Spike was her arch nemisis of hers.

She was beginning to understand that her actions towards Spike was total different. Like Buffy was turning her whole feelings around to pain,suffering,and turning to lust. I finished watching Season 6 Review with the cast & crew about the Season. Saying that Buffy & Spike's relationship was in total "Darkness", Buffy was the first one...