I don't think us readers have to worry about any sort of love triangle drama with Harumin. I mean, haven't you been paying attention to her character all this time? First of all, she hates confrontation, as seen various times in the original manga. She will never acknowledge her feelings for Yuzu, which are kinda obvious and not even that subtle imo (the feelings). Secondly, she is definitely the most mature and level-headed character of this series, emotion-wise, and the last person in this series who will most likely cause any sort of drama. So the point is, If Harumi has any kind of unrequited feelings for Yuzu, like most other people in this world, she'll get over it. I don't think she would be all angsty and sad for 20 chapters. That would be OOC (in my opinion). Besides, Matsuri will be more than happy to help her get over Yuzu.
Then again, this is Citrus, so...