I really don't like the position Shiho currently is in this relationship. It does makes sense for Aki to not have romantic feelings for her yet, so I can't complain about that, but I don't think anyone deserves to be with someone in the hope that maybe one day their love will be repaid. Also, considering Shiho's personality, it could lead to something bad. I guess it'll depend on how much the author wants to extend the story (and if they want to insert even more drama into the story), but it wouldn't be hard for me to imagine a situation where Shiho sees Aki and Yori getting along, laughing together or whatever (like Hima did at the beginning of the manga), and her insecurities and jealousy make her think "What would happen if Yori suddenly fell in love with Aki? Would Aki leave me for her?", or things like that.