Do remember that Larian have already said that, aside from having to work together to find a cure, there is little chance that the group would be travelling together.

Now I am not happy with the Companions from a romance perspective, and I think they are rather over-the-top in terms of backstory and quirks, but I can completely agree that they work as a disparate group who have nothing in common aside from hosting a tadpole. If you are wondering why they are in your party, then yes, that's a point that Larian have addressed.