I read so many manga where this type of story usually goes that the mc love interest falls in love with someonee else or they move away for some reason. I think the mc love interest for this story is that she will move away to pursue her music career and the mc gets left behind. Maybe the mc picks up the music thing from her and starts to play guitar or trumpet or any other instrument.
@WoodyCyber I saw the raws up to 15, since the chapters itself are short it's still ongoing, and neither one you mentioned. If I understood correctly, it has something with the girl has to move away, could be wrong tho.
@ElAleph probably his proactiveness and straightforwardness. Takamine is smooth but she's shown signs she has her own hang-ups, so i'm guessing she's admiring how he can face things head-on. do you find him unlikeable?