What’s commonly referred to as Taiwan is just a euphemism, and also includes parts of Fujian province.
The official name is Republic of China.
Thus China is a divided nation, just like North and South Korea or Germany in the past.
They just handle things differently due to the immense difference in population.
Back then any East German could jump the fence/wall and was regarded as a German citizen in
the West. That’s just not possible for R.O.C.
You never know how it eventually turns out.
The USA isn't the only one deporting legal residents married to citizens:
https://archive.is/MuPu4