It's true that the last chapter is sad as fuck. But the author is doing this so that we don't forget how things were in the past and how it still is in certain parts of the world, she's diving into a sad but true reality. Sensei is showing how in the past they couldn't even think about being together, in danger of being ostracized, denied by families ad society, and how now there's a possibility to be together and be accepted by all. Our main couple having a chance shows how the world has changed and how it must never go back to not being able to love whoever you want to love.
It's true that the last chapter is sad as fuck. But the author is doing this so that we don't forget how things were in the past and how it still is in certain parts of the world, she's diving into a sad but true reality. Sensei is showing how in the past they couldn't even think about being together, in danger of being ostracized, denied by families ad society, and how now there's a possibility to be together and be accepted by all. Our main couple having a chance shows how the world has changed and how it must never go back to not being able to love whoever you want to love.