We are trying to help you understand why some of us have mixed feelings on Gale but unfortunately it seems you are very dismissive of everything we say. I even gave you the comparison to Solas, not sure if you played Dragon Age. Solas is very much like Gale, yet he was a traitor. He manipulated you the entire time, made you think he knew nothing when he was the brains behind everything. That reveal was the biggest shock to the fan base, even though a lot of us love Solas, but he is what he is. It seems that you just don't want to accept the possibility that Gale could be the biggest manipulator of the group. He could be good to you for 95% of the game and not reveal his true intentions to the very end, just like how Solas did in Dragon Age.
This is not evidence for Gale being suspicious or untrustworthy though. This is projecting other characters' story arcs onto Gale, when Gale could actually be a Varric or Alistair or Vivienne. There's a difference between "accepting the possibility that a character can be lying and have hidden motives" and "believing that the character is lying and has hidden motives."
Niara, I think you're only considering info that is presented in BG3, not taking into account any meta-context (e.g., Larian's general NPC design/storyline decisions, common narratives for the smooth-talking, powerful, smart, and driven character). Whereas others seem to be considering this meta-context (see @GM4Him's post above). Neither is a wrong way to look at a character, as long as you recognize what sources you're considering and how such biases could affect further interactions with the character in-game. E.g., if you already are suspicious of Gale, then you'll become even more suspicious when you learn that he's studied Netherese magic because the tadpoles use that type of magic!
All that said, it's reasonable to be suspicious that Gale might sacrifice you if that would get him back in Mystra's good graces. I don't think he's planning on doing so, and he'd probably feel bad about it, but that is his driving force...besides you know, not dying.
