couldn't agree more, there isn't a single explanation about how they got together
And what if they don't explain? The story isn't about them, there are basically 4 mc. It's not a bl, it's a slice of life, it covers many themes and talks about the relationship between the characters. The ending is not rushed it just skips to years later and let's you know how they are doing and that they eventually got together. I don't think it's fair to say that this is bad for the ending, just because the story doesn't explain, cuz as i said before the main plot is about their high school lifes, their problems and their relationship and how they overcome them :)
i expected a masterpiece but wtf is this? how tf did they even get together and this is just my opinion but the ending felt rushed. overall i would have liked it more if we knew how they got together :/