Cross-Continental Marriages

I have a foreigner friend in China who has been dating a Chinese girl for about a year. They are very serious and are even considering marriage. Although, his girlfriend has never been to his country or met his family, and his family isn't too crazy about him living in China for much longer. They know that if they get married, they will have to choose to live in another country or China, and either way, one of them will be separated from their family. 

For those that are married to or at least dating someone from another country, please don't be afraid to share the advice!