I'm not sure if it's similar, but meeting Shadowheart as a drow, and as someone who tried to help her on the nautiloid, she seems to be less guarded than in other cases, and yet, she's back to her guarded self after.

Maybe a single measure—Approval—isn't enough to properly develop the relationships, although it must be simpler to use. Still it feels like you cannot make meaningful progress in the relationships until you cross the correct Approval threshold.