In the final scene with Buffy and Spike, when they're holding hands, and Buffy says: "I love you."
And Spike replies: "No you Don't. But thanks for saying it."
Before that she puts her hands into his(here's the part I noticed)and soon after, both palms burst into flames, and she's overwhelmed with emotion. As I watched her stare into the aflamed hands, I couldn't help but be reminded of th musical no. "Walk Through The Fire" and think back to the lyric: "I touch the fire and it freezes me. I look in to it and it's black. Why can't I feel my skin should crack and peel. I want the fire back."
Maybe it's just me, but I took that scene to be the moment Buffy gained perspective on being back into the cold world after being resurrected from Heaven. It was the pivotal moment in which she found closure on her whole 'state-of-being'.