I’ll second most of what Hemlock said. In Japan as well, the WM/AF couples far outnumber the WF/AM couples. A large part of that is simply that more men than women come to Japan from the west, but even so, many western women I’ve talked with have complained about the lack of acceptable dating partners, whereas I’ve hardly ever heard guys make the same complaint.
Why? Pure speculation, but…
Family obligations may have a lot to do with it. Traditionally, wives become part of the husband’s family and are frequently expected to do whatever the new mum and dad tell them (especially if they’ve married the eldest son). If the wife is a westerner, there may be more occasions for wife vs. in-law culture clashes over how to run the household and raise the kids. When a daughter marries a western man, OTOH, her parents may be more likely to consider their daughter ‘grown up and gone away’ and not try to run the show (I’m ignoring the western in-laws here, but since I’m living in Japan, there’s not a whole lot my parents can do from 8,000 miles away. A/W couples outside Asia are another question).
I’ve had some interesting conversations with my housewife students about this. When it came to their daughters, many of the moms wanted them to marry foreigners (specifically me, in a few cases). There was a general perception among them that western guys were more romantic, more communicative, and took a more active role in raising kids and sharing household duties (A few of them also said they thought western guys were better in bed. I decided not to push them on how they made the comparison, but did nothing to dissuade them ;)) Of course, most of this was just based on movie images and media stereotypes, and I tried warning them against setting up false expectations, since there are more than a few guys here who have the “mail-order bride/submissive little kitchen slave” attitude TheLoadedDog mentioned.
When it came to their sons, however, their attitudes suddenly changed. Almost all of them wanted their sons (eldest especially) to marry Japanese women, usually because they expected the daughters-in-law to move in and take care of them when they got older, and worried that there would be too much cultural friction with a western daughter-in-law, or that the DIL would want to move the husband and kids back to her home country. The ones who weren’t opposed usually had sons that were working or studying overseas and had accepted that they had left the nest. Even then, the kids in question were usually second or later sons.
My (Japanese) fiancee just passed by, so I asked her opinion: “Asian women are better at English than men. And we’re smarter.” Well, there you have it.