I agree the fight was forced but Willow did go against Tara's wishes in revealing the book that Dawn used to try and resurrect Joyce to Dawn. I think Tara found out or strongly suspected. I should have been made clearer though.That's what I love about the final four episodes of the season is the why they build the odds about Buffy and the Scoobies, and just how powerful Glory comes across as.
This is a good personal episode for Buffy in stepping up and making the tough decisions for Dawn as a Mother figure. The scenes with Tara and Willow are so touching. I do agree that the fight was forced. But to see just what Tara is put through and Willow's heartbreak is a big moment for their relationship. It's a nice touch than its Spike who points it out to Buffy that pretty much anyone would seek vengeance if that happened to a loved one. Think this is the start of a much darker tone for the show.