I'm considering proposing to my long time girlfriend who is a legal alien, originally from Hong Kong. We are not rich but are not poor either. One of our future goals if we do get married is to own property in both the USA and Hong Kong. I know that being wed in the US means she gains US citizenship but first, what is the application process for that and is it costly? Second, would I also gain citizenship in Hong Kong? What type of papers would be required to request this type of dual citizenship.

Last but not least, if something did happen and we were to be divorced, would I/she maintain our citizenships to each others native countries or would I be forced to sell any property I bought in Hong Kong?