准老婆，未婚妻 的英文怎么说？

未婚妻: fiancee, wife-to-be, a lady engaged for marriage, a woman under a marriage engagement agreement, someone engaged
准老婆: future wife, the ideal life partner, future lifelong companion, my sure wife

Interesting. I have never heard quasi-wife. Quasi is not everyday English. When we refer to a non government organization (NGO) but funded and regulated by the government, e.g. lots of tourism boards, we call them quasi-government organization. Another example is when we retire from our permanent job but agree to return on contract, we lead a quasi-retirement life.

Quasi means similar but not real.

准老婆 means a girl you will marry soon, so we call her wife to be.

未婚妻 is finance after the engagement. Most Chinese don't do engagement ceremony though.

One more term: partner. In China, most refer partner to someone you do business with, i.e. a business partner. In the English speaking world, a partner is someone of either sex