It's very obvious that Larian is setting up characters to encourage intraparty conflict. It's far from the normal approach to rpgs, but in theory it should result in more dynamic relationships than you see in most crpgs.

Really though, I feel like this is runoff from an issue I see spreading across most forms of media. Everybody seems to want to cash in on the success of Game of Thornes, so stories become dark and edgy with untrustworthy backstabbing characters. Rather than politics Larian went with party relationships.