Yeah the ending felt more like banana fish. Tho i don't consider the end as something shallow. They're both been through a lot. The uke might have suffered from what the seme did but in the end, during the confession, he understood everything.
I don't think the ending is shallow at all. Read the author's notes- there was a lot of thought and symbolism put into it, and it was purposely ambiguous. Tbh in BF, Ash's death was honestly so random and surprising, I thought that was more shallow.
Sorry nut, the ending is a bit shallow. Reminds me of Banana Fish but BF has better reason for it's ending, I think