I think it was in character for Buffy to accept Riley's assessment. She blames herself. That's the sort of person that she is. I always struggle with how much to blame Riley and Xander for Buffy blaming herself, because they aren't in control of her feelings. You can't blame them for her feelings. And yet they both behaved badly, and she was hurt badly by it. It's a very tricky thing.

There are other points throughout the series where emotional shifts or key events are handled awkwardly or abruptly, and seem to exist as quick ways of moving the plot from A to B, as well as create a moment of high drama that may be received emotionally by the viewer, but not in the ways M.E. intended, so that the viewer ends up feeling uncomfortable, manipulated, angry, or has to disregard said point altogether to lessen the cognitive dissonance.

I know exactly what you mean, and very well put. It makes fannish disagreements very intense. But weirdly, it also feels kind of realistic for me--because in real life, the loose ends don't get tied up neatly, and figuring out who is right and how is wrong is never simple.