When two different cultures come together, you can expect some friction in the process. If you are a Western man seeking Vietnamese girls to date, then you need to be very careful when dealing with the following cultural issues:
One of the first and foremost things you need to be cautious about is the behaviour you exhibit around Vietnamese girls. What may be appropriate and inappropriate in your country may be the total opposite in hers, so do your research before reaching over to kiss her cheek or give her a big hug. This is especially true for more intimate gestures like kissing, and petting as these are perilous waters to tread if you do not know what you are doing.
Another serious date-buster is operating on assumptions based on racial stereotypes. Not all Vietnamese girls are prostitutes that can be won over with money and gifts for Viet dating, and neither are they all mild-mannered when it comes to their behaviour. Women are women, no matter where they are from, and it would be to your advantage to learn more about the girl you are dating before coming up with any assumptions.
Religion is also a severe matter for Vietnamese and Western men alike. A date is not a mission to convert, and neither is it a venue for religious debate and dialogue. While broad-minded individuals can engage in some light discussion on religion to spice things up, avoid getting in too deep in the spiritual talk. This is especially so when your relationship is in the earlier stages of development, as you may find yourself in some serious trouble if you say something wrong about a person's religious beliefs.
Family is another very delicate issue for Vietnamese in general. While not all Vietnamese are very family-oriented, the majority of Vietnamese have close family ties. Berating a family member is like berating them as well, so be very careful when the topic of family comes up. Viet dating girls are also particular about settling down and raising a family, especially when you get them pregnant. Get everything straight before engaging in the act if you do not want to find yourself forced into a shotgun wedding.
While the boundaries of style and clothing are quickly beginning to blur thanks to the global spread of fashion, it is still worth taking the time to understand the cultural understanding and implementation of way where she comes from. This is especially so for clothing that has deep cultural and religious significance to them. So do not force your partner to adhere to a particular fashion style if she does not agree with it.
Last but definitely not least is the topic of work. Do not belittle any profession that your partner chooses, whether it is being the CEO of an international company or being a dedicated homemaker. Cultural norms are particularly strong when it comes to Vietnamese girls, so avoid being too attentive to her choice of career. Support her decision, and you will do just fine together.