Hostility isn't a pleasant way to have an innocent discussion.
Why would Aqua have any inkling to think her master was wrong? She was practically raised by his hand. Eraqus was just as dear to her as the others were. Aqua has every right to accuse Terra of that because it was happening. Eraqus wanted to keep an eye on him in case he did fall. Aqua was sent to watch over him. Is that really terrible that Eraqus was worried about Terra? It isn't like Aqua is hampering Terra in any way. She is just looking out for him. He needed it.
Ven is an asshole in that accusing too. Does he even bother to wonder why Aqua is worried? Hell no. He belives Terra and only Terra is right and Aqua is a stupid bitch. Terra and Ven are horrible towards Aqua. She just wants to keep everyone safe and they attack her as if she is hurting them.
I don't think it's
what they did; you're right, Eraqus and Aqua were only worried, and they had reason to be. It's
how they went about it.
First, Eraqus tells Aqua these orders
behind Terra's back. Terra wasn't aware he was even doing anything THAT wrong, so finding this bit of information would have been a huge blow, especially coming from the mouth of one of his
best friends.
Secondly, his first meeting with both of his best friends (save for that short conversation with Aqua 3 worlds ago) was to find out one of his best friends had been ordered to spy on him by his practically father figure,
and she was perfectly okay in doing so. True, she had good intentions. But hearing that she spied at all would have been tough to take; I'd be pissed, too, especially as, like I said, he didn't know he was even doing anything wrong.
And lastly, Aqua all but denied that she truly was spying on him. When Terra came up with the accusation, she didn't try to deny it, she tried to
justify it. It's pretty much the equivalent of, "Yeah, I was spying on you, but this is why". That wouldn't have sounded very good, either, finding out his best friend was spying on him.
As for Ventus, I do agree that he overreacted. At the same time, I can also see and understand why he would. His brother/father figure is being accused of some pretty awful stuff by his own sister/mother figure. He's trusted them both so much and never had any reason to distrust them. All of this coming to light out of the blue must have been pretty hard for him to take in, especially at that age. And since Aqua was the accuser, with Terra being the accused, Terra looks more like the victim here, while Aqua looks like she stabbed them in the back. Add that to him being closer to Terra than Aqua, and it's pretty obvious why he would act that way. Yes, we may disagree, but we're also third parties and can understand the situation a lot better than all three of them, because we can see everything in a much larger perspective while they can't. We can't expect them to understand the situations like we do, because they aren't presented with what we're presented with; they don't have that information.