I do hope Elrich and Cabel remain just doting brothers than guys with a crush on her. I can accept Eugene, as he was away from her for 6 years (with occasional visits) and was hinted to have developed a crush on her before he could start seeing her as a sister, but these two should just remain bros. They can be crushing on Louise instead ;P
(though the novel's cover art doesn't give me too much hope...)
Either way, I feel sorry for Johan.