Buffy felt lucky that the Dome had afforded them that small luxury. It could have easily been a much tougher situation. Different places in the timeline tended to cause those kinds of problems. At least that was one thing Buffy didn't have to worry about. A shared history from home was a good starting point, especially given how much she had to tell him about their lives in Madison Valley.
When Buffy did say those words to Spike, watching him burn to ash before her eyes, it had been different. She felt it, but there never seemed to be the right moment or time to say it to Spike. They were facing down the fight of their lives and everything and everyone came first before what the two of them wanted for themselves. And truthfully, Buffy wasn't sure if it was love she felt then. There was so much mess in their history that she wasn't sure of her feelings until Madison Valley had allowed her to more fully explore them. Now she knew without doubt how she felt about the bleach blond vampire seated in front of her, but back then? It had come in the moments before she knew she might never see him again. A desperate last moment's grace for them both.
"Spike, you don't know-you don't know everything that happened in Madison Valley yet. When I said those words to you back home, I never thought I would see you again. I knew it was my last chance. And everything was such a mess back home. There was never time, never the right moment for me to tell you and to talk to you about any of it. We were fighting for our lives and everyone came before us. And I honestly wasn't sure how I felt or how to explain it to you." Buffy was being honest with him about all of that. Madison Valley had helped her to realize what she felt about Spike was real and that it was love. That was why she could say it to him now and mean it. This was not the version of Spike from the past few months, but it was still him and while it would take time for anything to happen, Buffy did love him. That part didn't change.
"But that's not the case now. And coming to Madison Valley, I had the chance to realize a lot of things. I had the chance to really look at what I felt and I know now what it meant. I do love you, Spike. I do. I know you are different obviously than the Spike before you, but that doesn't change that. I do love you. Things will be different, but that doesn't mean that changes because it doesn't."