What Stretch was in the end was Yuri Crush which occasionally rose to Romantic Two-Adult-Women Friendship, I think. The sempai was very damaged (with some mental illness, even) and it was an open question whether, if they'd stayed together another year or so, they'd have tried out being a couple, I think. The kouhai (also damaged and verging on alcoholism) was clearly head-over-heels in love with the sempai. They made no bones about that. That said, it was a vehicle to draw out a huge yuri tease over ages and ages, it definitely made you root for the kouhai, so it was understandable that most of us were dissatisfied.
Yuzumori-san is a different case. The best outcome is probably they stay friends only, and some distant epilogue has them getting together. The second-best outcome is a sneaking relationship relationship which would make the series even more dramatic than it is already. So realistically, a full-on yuri tease isn't even believable nor would it be effective. The subtext is that Kaede, though a grade-schooler, is basically as mature as Mimika, a high-schooler. So she has it together enough to figure out a way for them to go forward, if the misunderstandings can be cleared up.
Also, I think it's too unbelievable that Ririha is even yandere for Yuzumori-san. Basically the most sense I can make of it is that she's so narcissistic she doesn't even know herself why she does anything. At a stretch, I guess the "only I can bully her and ruin her life, not you" thing might be plausible. They've made her a manipulative sociopath hiding behind her little-girl status and with minor blackmail overtones, and it's hard to walk that back.
