Spike saves Dawn in Gift dying in the process.  Dawn is devastated, Giles is curious, and Buffy is only mildly sad.

Must have a conversation between Buffy and Giles about what it means that a soulless vampire sacrificed himself to save her sister that makes Buffy stop and think.

A conversation between Buffy and Dawn about what happened up on the tower, and Dawn accusing Buffy of being heartless for not acknowledging Spike's sacrifice.

147 days later the PTB bring back a feral Spike who only responds to Buffy and Dawn.  While they nurse him back to health he is very affectionate of the two girls, nuzzling and what not.

Giles wonders what it means that a soulless vampire is brought back by the PTB and decides to ask the Oracles, but since a champion must petition them, Buffy has to come along.  The Oracles reveal that Angelus' curse was a way to curb his evil tendencies until he fell in love and that losing his soul was a test of his love.  When he failed, they brought him back so he could continue on the path of redemption, but they knew he would never be able to fulfill their needs.  They decided to try again, but with a chip that essentially didn't change the vampire's personality, but allowed him to get close enough to a human to love.  Spike past the test when he died for Dawn.  They reveal that he is chipless as part of his reward, something Buffy hadn't considered because he hadn't attacked a single person, even in his feral state.

Buffy takes the news badly and when she spouts her epistemology on demons' inability to love the Oracles treat her with disdain and threaten to have her chosen status stripped as having someone so blatantly bigoted is a detriment to the balance they are trying to maintain.

Shocked and confused, Buffy runs to Angel and demands an explanation.  He eventually confesses that it wasn't that Angelus couldn't love Buffy, he merely didn't love her.  Of course, he covers by saying that he as Angel loves her very much, but her entire foundation is rocked by the revelations.

Would like to see Buffy retreat (perhaps to the desert) for extensive soul searching.

The reason the PTB are performing their little experiment in vampiric love can be up to the author.  However, if it is meant as a way to pair slayers and vampires in the future to ensure longer survival of slayers (Which means Buffy is the beta test, lol) then perhaps they show her how her life should have been if Angelus stayed true to their love.  No Acathla, Mayor's easy defeat, Faith doesn't go bad, Spike doesn't get chipped, Riley doesn't lose himself in insecurity, yada yada.  When Buffy asks to see her future now, they refuse, telling her they won't influence her present and future decisions, they can only show her what could have happened.