I see having an option in settings to let you know if a choice is good or bad but I think based on the writing and the dialogue choices, it's pretty obvious what is good or bad. As for what choice a companion will approve or disprove depends on their alignment. Are they good or evil? For example, Gale and Wyll are aligned on the good side, so you tend to make good choices if you care about their approval. Lae'zel's alignment is evil so if you make choices that seem mean or evil, she will most likely approve. As for Astarion and Shadowheart, they tend to be neutral a lot.
