
Bruh I’m reposting this cuz it needs to be SAID! The way I interpreted it is that Yuki left a big impact on Mafuyu’s soul. Mafuyu still loves and can’t forget about the memories of their past, but it’s not a romantic love anymore as it used to be. It’s more like memories you cherish with someone you used to love romantically. But as seen in recent chapters, Mafuyu, even tho he had the fear of moving on and forgetting those beloved memories, realized everything has a beginning and end—and the end of being stuck in the past was approaching for him.
In his most recent song, he conveys it is time to move on as he has found a new passion and love to cherish, and it is time to let go of Yuki’s hand with the hopes of only leaving the precious memories remaining. It is quite obvious that Mafuyu is still not over his death, but it’s no longer out of romantic love, but more that both of them belonged to each other and filled a part of each other’s heart. That’s why it’s hard for Mafuyu to move on, even if he loves someone else now.
Think of it as when one’s previous best friend or mother dies, and how there will always be a gaping hole in the heart only that person can reserve despite finding someone new to love. I think Mafuyu’s boyfriend is writing the song to find closure for all of Yuki’s friends as they had revolved around him and had a special place in their heart for him. The love Mafuyu has is no longer romantic, but it is still love one held dear to their heart, and his boyfriend writing the song in hopes for achieving closure for everyone symbolizes the beginning of a new life and actually achieving the phrase “moving on” (though Mafuyu’s previous song talked abt it, it was more like he had decided to finally move toward but still hasn’t). So honestly I think the progress in recent chapters is nice and realistic, cuz no one is going to forget abt someone they loved so deeply in their heart so quick even after a situation where they start loving someone else.
But what they do need is closure, and Mafuyu’s boyfriend finishing Yuk’s song is the perfect way for everyone to find their peace with Yuki’s death and finally taking a step forward without any lingering feelings but happiness (such as starting a pro band). Honestly I’m still confused on why Yuki died (alcohol overconsumption or did he kill himself psychically) and his motives behind it. I think he was just a person acting on impulse many times.
Or perhaps in situation like a chicken race—where he didn’t yield to Mafuyu in the fight out of pride—Yuki ended up succumbed to pride and thus met he death impulsively. Yuki’s character seems truly complex and fascinating, and it’s no wonder his singing was exceptional and his emotions are now carrying into so many people and making them grow and become talented in the music field.
Ugh there’s just so much to process in this manga and it’s so hard to get the words out cuz it’s just so complex man. You have to really think abt this shit.

It's not that Mafuyu lost only his lover, he also lost his best friend. Seems like people tend to forget that part. To Mafuyu Yuki was so much more, they had been together since childhood, they were friends, they grew up together and they experienced their first love together. Losing a person like that leaves a scar that will never heal entirely, it will fade in time but Yuki will always be part of Mafuyu. It's a painful and hard situation for Ue and Mafuyu both but Ue acts very mature, considering that this is Ue's first relationship -and the fact that his love interest is same gender, something that Ue did NOT expect for his first love to be. Love is never an easy thing, for Ue this is all new and he must be really confused. Still, given the circumstances I think our boys are doing really well.
Mafuyu also has his own inner conflict and guilt: if I really loved someone that much, would it be disrespectful towards my lost love's memory to eventually evolve such a huge emotion towards someone new? Am I allowed to love again? Will falling in love for someone new mean that I have gotten over my loss? Do I want to get over it, would that mean that I will forget someday? Will I forget? If I do get over it, would I feel like I need to be forgiven for falling in love for someone new? Can I and will I forgive myself? Can I give myself a permission to move on?
And I think we got Mafuyu's resolve in the anime, the lyrics he wrote "Fuyu no hanashi". Mafuyu chose finally to step outside from that isolated place where his time had frozen after Yuki's death and is moving forward. It doesn't mean that he is not allowed to never look back. These boys need time, Hiiragi and Shizusumi as well. Those two also have someone new in their life. Surely Uenoyama will never be able to replace Yuki, not as a friend, a band member, or lover, and he is not even supposed to. Uenoyama doesn't need to try to fill Yuki's shoes or follow his footsteps, all Ue can do and needs to do is to walk with them, by their side and hopefully they all can move forward with somewhat less painfully. They are learning to move on, they are learning that it's okay to move on and that it's not something you should feel guilty about. They all still have their regrets and they still are learning how to forgive themselves. And they have grown so much, I'm proud of our boys

Thank god someone said it! A lot of people are so biased like fuck off give my child a break! And you're definitely correct. This song will make a huge impact to Mafuyu and Ue relationship. Yuuki is a huge part of Mafuyu's life so he can't just forget him. But he needs to let go of him. And this song will finally do it. This song will allow Mafuyu to let go and move forward with Ue.
that song is essential so mafuyu and uenoyama can move forward
i don't understand why some people are attacking mafuyu give him a break
especially if you haven't lost someone dear to you without patching up things with them
moreover if the last words you've said to them had an influence to their death
and that you have to carry both an abstract and tangible burden with you for who knows how long
until you can finally forgive yourself and move forward
easier said than done to say mafuyu should already move on
healing takes time and it's certainly not something that can easily be achieved
for only a year in mafuyu's case
the memories are still fresh and you have to deal with different kinds of emotions
you want to move forward but feelings like guilt, fear, and anxiety haunt you
before yuki died mafuyu didn't understand why he was so devoted to music
he probably felt like he was competing with it and that's why he said those hurtful words
yuki's guitar served as a memento for yuki who loved music but at the same time
it was also a reminder of the things mafuyu didn't understand about yuki
so he wanted to learn it kinda like a salvation
uenoyama is his salvation he made him understand where yuki's devotion was coming from
all the things mafuyu refused to understand before he understood by being with given and with uenoyama and slowly he's able to sort his messed up feelings through their songs
it was probably the same for yuki as well
all the things he wanted to say that couldn't reach mafuyu he wanted to convey it through a song
because isn't that how we understand another's and even our own feelings better through songs?
but unfortunately he wasn't able to finish it
that's why uenoyama finishing the song means a lot so mafuyu can put a closure to his past with yuki
so don't say such immature things like mafuyu is the one to blame here
uenoyama had a choice whether to complete or not to complete yuki's song
but after hearing it he probably felt like he needed to because out of all people
he's probably the only one who can best understand and turn yuki's feelings into a song
thank you for listening to my ted talk lol
i feel refreshed after writing all that
i just felt like i had to protect my sons