I feel like it’s more open. The MC was scared to say he was his father as he was also afraid that he wouldn’t be a good parent due to his mental instability. So he just left it as being the friend of the ML, but I don’t think the kid never will know. It’s likely he will eventually know when he grows up- it’s just that the story didn’t show that confession leaving it on a more realistic note for the time being
I read the raws and it's only chapter 44 with no side stories I'm satisfied at the same time not with the ending BUT I'M OK WITH IT