Personally, in this discussion, I do not equal "trust" with liking a companion or agreeing with them; for me, it is more like "do I know where I stand with them?" This is more easy with Lae'zel, who is very direct, and also Astarion (even when he is trying to be a bit more manipulative, it is so obvious I can hardly call it that at all). They do not even try to be "nice"
how interesting, i never try my companions stand in front of the magic mirror, and i will have a try!
maybe i can intercept my companions' desire, such as i get mystra's favor, i bind mizora serve me, ... and so on.
that will make me the most sworn enemy of gale and wyll.
and this doesn't violate my belief -- i never and will never sign dark evil path(such as helping goblin camp) i am a true neutral one for the toril balance.