Wow that's really harsh.
I'm curious now, why do you think this?
*(and I'm not counting Angel s5 because frankly that can all be summed up to plot convenience that they didn't get help from Giles and further more we never heard his side of the conversation and can't judge only from Angel's reaction since his feelings were clearly already stirred)
What's harsh about Buffy dealing with what happened and working past it? I didn't mean to imply that she forgot or ignored what had happened in Season 2, merely that she was both more able and willing to forgive Angel for what happened.
And as far as Giles never truly forgiving or trusting Angel again, for me at least, this is quite obvious. Up until Angelus returned, I really believe that Giles had pretty much stopped thinking of Angel as a monster and saw him as more or less a hero with weird dietary requirements and an extreme aversion to sunlight. There were vampires, and they were monsters. Then there was Angel, and he was a hero. (A bit of an exaggeration, but I think that you see my point) Then suddenly, and under very tragic circumstances, it was reaffirmed that the only thing that separated hero Angel from monster Angelus was a soul that was not as permanent a thing as they had all come to believe. Giles was like the man who had been bitten by the beloved family pet. He never again had the same level of trust in Angel that he previously had, and the fear of Buffy some day ending up like Jenny Calendar, or worse, always haunted him after that.
And we can't disregard Angel's Season 5, nor the results of Season 8, simply because they do, in addition to filling the role of plot convenience, reaffirm Giles' ongoing distrust of Angel. Likewise, we can't disregard Giles' continued distrust of Spike in Season 7, (I HAVE to bring Spike into this to make my point, not to try and start another Bangel/Spuffy debate) even after he found out about his having a soul, because that, also, serves to illustrate the same thing in Giles' mind. Vampires may have souls, and they may, at the moment, be fighting on the side of good, but the fact remains that vampires are always going to be classified as monsters, and monsters can never be trusted completely. Angelus taught Giles that, and he never forgot it. When Giles told Buffy in Season7 that he "wanted so much more" for her, he wasn't just referring to Spike. He wanted "more" for Buffy that a life with a potential monster. ANY potential monster.