For me, the story ended in the last chapter.
MC went along with shirt haired girl to America.
And fMC though broken hearted realized why she lost to the short haired girl, the only thing she had to offer in the relationship was sex, which clearly isn't enough. Therefore started studying seriously, found a good boyfriend. And moved on.
This is the most reasonable ending I can think of, there is no way in hell both of them would be still stuck on each other after 3 yrs, after what happened