The following scene in the episode after the country house where Miyuki unpacks the story of Kaori to Nagasi in detail (from her point of view), holding nothing back, causing her to cry endlessly.
When Miyuki tries to force Nagisa and Tamao to become their school's Etoile candidates. This causes Nagisa to run to the greenhouse and look to her love, Shizuma, for reassurance. After expressing her continued feelings for her, Shizuma's reply is "Forget about me" causing Nagisa to run away and cry herself asleep into Chikaru's body alongside the lake.
Although Hikari forgives Yaya for her previous sexual harrassment, she's naturally still scared to get close to her after that. The way she visibly flinches around her, and Yaya's guilt ends up in her refusing to go to the Etoile competition, with Tsubomi comforting her so she won't have to be all alone.
Right before the Etoile Election. Amane is meeting Hikari where they first met. She's rushing over to tell Hikari all her feelings, her stirrup breaks, she falls off, and hits her head. When she awakes (from Hikari's tears hitting her face), she doesn't remember Hikari or their love at all.
The ending where Tamao pulls an I Want My Beloved to Be Happy, undoes her ribbon, and pushes Nagisa toward Shizuma. They run to each other, embrace, and run off together; then we get a cut back to Tamao congratulating them but looking utterly heartbroken.
Episode 26 - The Stinger: Nagisa and Tamao stand silently on opposite sides of their door. An obviously hearbroken Tamao forces out "Welcome home... Nagisa-chan." While the overall is Happy Ending, the scene is a Sudden Downer Ending, and is the last scene of the entire show.