It’s much easier for us to feel the passage of time moving on for us because we live in the real world and it has been years since we’ve been invested in this story. However, do keep in mind that within the world of Given, it literally hasn’t even been a YEAR since Yuki died. Yuki died in the winter, then 4-5 months later Mafuyu met Uenohara, and now it’s finally just coming BACK to winter. It’s the season Yuki died. Of course they want to give him closure by playing his song and all. Mafuyu is the only person in this manga so far to have “let Yuki go” while the others have had no chance to do so yet. I believe Uenoyama, Hiiragi, and Shizu will be able to let Yuki go after they perform his song on stage, just like how Mafuyu did earlier. Give them time. It’ll be over one day.
I've never seen a dead character more alive than Yuki in my entire yaoi career. I don't "hate him" perse, but mf be haunting everybody inside and out of the story since chapter one and he's not even alive. Like, please, i know that it takes time to heal. More so when all the characters are finding out their feelings right after Yuki died, but as a reader, I'm exhausted. I'm tired. I need them to move on a little faster. I know high school life can be chaotic. Even more when going through all they've been through, but! Come on! They still have to show us Mafuyu's reaction to Yuki's song and I'm like PLEASE HE'S DEAD, LET US ALL MOVE ON. I CAN'T DO THIS ANYMORE!