After several times in China teaching, no one ever made a pass at me or tried to marry me.

That is indeed very fortunate for you.
If you need a Chinese girlfriend/wife, it's far better if you look for one yourself, rather than to wait for one to find you. When the fair sex does the chasing, re a westerner, there's usually an angle for their benefit driving it. And that will probably compromise your own interests. That said, Western males should exercise caution with all women, but especially with Asian females. Golddiggers in that group abound!