In Marriage Story, both characters face a great deal of pain and loss. Their marriage is falling apart, and there are many negative emotions involved. They have to deal with lawyers, custody battles, and their own personal issues. So, happiness is not what they end up with.
Langa and Reki do end up together in the manga. It's a satisfying conclusion for fans who have followed their story closely. The plot twists and turns lead to this heartwarming ending where they are united.
In the manga, Ishida and Shoko's relationship develops gradually and eventually they end up together. It's a heartwarming conclusion for their story arc.