First I would suggest you take a look at the HK immigration website to find out what the status of you SO will be (significant other not Second Officer LOL).
I know a few expat couples who are friends of my parents. There doesn't seems to be any trend towards the woman being unable to find work here. Of course these people came here a long time ago and are now all perm residents.
English is not as important as it once was. This you'll notice from more and more Ads being Chinese Language only. In the end it really depends on your SO's skill set. If she has skills that companies where the operating language is English wants, she'll most likely do ok.