Honestly, I loved this manga. It started really simple with two childhood friends getting together, but somewhere along the way, it evolved to childhood friends really getting to know each other more in the little time they had left together.
Yuuki proposing to Natsuha like that really showed what made this manga unique. They really love each other, and they trust that their feelings won't change in 4 years.
The ending montage of their wedding, their life together, Natsuha's pregnancy, and finally Yuuki and Natsuha's children was really cute. Even if the series was short, this really felt earned.