Hypothesis: Buffy is acting OOC in #36 (specifically she isn't acting like herself when she's around Angel).
1.) When Buffy's with Angel, she describes what just happened in Twilight (birthing a new world, then giving it up to go back and fight to save the old world) as the "weirdest, bestest, weirdest, best day of [her] life." She looks ecstatic and, in my opinion, disturbingly happy:
2.) When Buffy's with Spike, they talk about what just happened in Twilight (Buffy birthing a new world, then giving it up to go back and fight to save the old world) and Buffy begins to retreat into herself defensively, hugging her arms around herself and looking chagrined. Then finally as the ramifications of her actions hit home, she looks like:
Those are TEARS in her eyes. Buffy is crying and looking scared, even horrified, at the thought of what she's just done on the "best day of [her] life." So horrified that on the next page Willow is comforting her in the background.
Conclusion: Buffy displays two diametrically opposed emotional reactions to the same topic of discussion: Joy with Angel, despair with Spike. The two opposing reactions appear situational and the only difference is who she's talking to: Angel, then Spike. Either Buffy's having a bipolar day with some added hysteria or some outside force (say the influence of Twilight?) is manipulating her emotions so that the same thing she calls the "best day of [her] life" when she's with Angel now makes her cry in Spike's presence.
Long-term Outlook for Spuffy Fans: Fucking AWESOME. Spike is the one who grounds Buffy and brings her back to reality. Spike is the truthsayer who helps Buffy reconnect with her emotions. He breaks through the Twilight-induced haze and is now taking Buffy to the Hellmouth because "where the heart is... is home." Spike arrives and puts an end to this Twilight crap (Buffy and Angel's fantasy world faux "love") and is helping Buffy to reclaim her heart by taking her home. Spike brings tears to Buffy's eyes, just as (molly_may points out in her brilliant Season 7 Spuffy picspam) Spike is the one who gets through to her in Touched and gets her to open up and emotionally come to grips with her situation (Molly May: "There are those tears again!).
It's important to note that Buffy is coming off of a Twilight-induced haze that's pushing her to be OTT in love with Angel (they frakked in space and started an apocalypse!) when she first meets up with Spike again. She's harsh with him initially (she's still not in touch with her emotions), but note also how Spike is all business and gets right to the "heart" of the matter. He's trying to save the world and, I think, also save Buffy--"You can under no circumstances trust [Angel]." Buffy can't trust Angel or herself when she's around Angel. Now, this doesn't mean that Spike doesn't care about Angel, too, just that he's trying to save the world (good on him for having the right priorities!), he needs Buffy to do it, and in order to get Buffy cooperating, he has to keep Buffy and Angel apart.
This is a good thing for Spuffy fans because Spike helps Buffy connect to what's REAL: her heart and her mission.