Right now, Buffy's head is nothing short of a whirling mess. On top of the memories from home, and all the other things that prompted her to start smashing herself into the barrier in the first place, this, what just happened, is almost too much.

When Spike died, there was all this unresolved emotion - she'd finally learnt to trust him, she cared for him, she could let him hold her and feel safe, she could spend an entire night just looking into his eyes... and then he was gone. She never got to have that with him. Being around him now makes her confused, awakens all these old feelings, feelings she really shouldn't be having, because she's with someone else, who she loves.

It takes her a moment to find her voice again, and when she does, she steps back out of his arms. "No, it's not-- I'm sorry, Spike, I-- I can't." She really has to say this, and she should have said it sooner. "I'm seeing someone."