WHat are the names of the episode names of when Buffy turns invisible and the one where everything Willow says does happen(such as Giles going blind and Spike & Buffy getting engaged and the seasons they're in

I see this thread is about a month old, but in case you haven't found the episode titles yet, the Willow one is season four's "Something Blue" and the invisible Buffy one is season six's "Gone."