I'm going to bring in the truth, Disney does not know how to do familial love. I don't know anyone who act like Elsa and Anna, it's the same uncomfortableness as that Christmas advert, because you don't keep telling your sibling how much you "love" them while looking deeply into their eyes.
The blame can divided in three places, Disney, for always writing romance, without considering to change the formula. Trying to copy the play "wicked" which is based on a lesbian fanfic. Doing a bait and switch and putting the buffer there to say oh they're two girls, of course it's not romantic, let's go further, they are siblings, you are just dirty minded anon, now buy the merch where they are surrounded by hearts and out does madoka magica on gayness levels.