When the episode aired, people either loved or hated that speech, and the ones who hated it often said that it just didn't sound like Spike's phrasing - they were trying too hard to parallel Riley's speech. They had Spike echo Riley's "You say the words, but I don't feel it," lines, too, so I think they were deliberately making a parallel between the two of them - both of them end up leaving Buffy, convinced she doesn't/won't love them no matter how much they love her. Of course, Riley leaves her to deal with Glory on her own, and Spike saves the world in leaving, so it's not all parallels.

What it means that they were making that parallel, and what it's supposed to say about Buffy... I don't know.