My long held hypothesis is this: the companions in Bg3 are plot hooks.
Maybe, perhaps, could be. As hypotheses go, I like it.
Oh, imagine the uproar; the tears; the outcry; the wailing and the gnashing of teeth if, after spending most of your money on a bunch of chocolates and a box of flowers and spending all your spare time on the lovey-dovey romancing, suddenly - BOOM and your erstwhile sweetheart either shits in the nest and turns rogue or is killed by person or persons unknown. Deep joy.
Mind you, that will be nothing compared to what I will go through if they do a runner with the gear I gave them.