Maybe it's because incest isn't looked as harshly in Japan? Maybe. But they DO look cute together, romantic or not.

First cousin marriage is still legal in Japan. It's extremely rare nowadays, but it's not prohibited. It's not seen as incest.
And you may be surprised that it is still legal in some states in the US, and no, those states aren't all in the south

(I'm a southerner and am quite aware of that northern stereotype

You may be shocked to learn that some of the states that allow first cousin marriage are in the northeast... Wikipedia actually has a good comprehensive state by state table on this very subject:
http://en.wikipedia....States_by_stateMy home state of Kentucky actually has one of the tougher laws- since 1943 it was no longer legal for even first cousins once removed to marry, something only 3 other states prohibit. (That kind of cousin marriage was quite common prior to the 20th century in both the US- amongst all social classes, and in Europe amongst the upper class. In the US it was more a factor of most people lived in small towns and traveling outside of that was an effort, so chances were you would be related somehow to the person you married. In European upper classes it was more about keeping property in the family. In the US property laws were less rigid than in Europe, so wealthy American families were more likely to marry within their social class, but to families not as closely related.
In Japan the upper classes, especially the nobility, tended to marry relatives like upper class European families, while in villages the situation was similar to American small towns. Artisans and Merchants tended to follow a different pattern, where, if there was no son to carry on the family name, a promising apprentice would be adopted into the family and would marry a daughter. (mukoyoshi)- this could happen in the upper class nobility but was most common in the artisan and merchant classes.
Dream you dream alone is only a dream, but dream we dream together is reality- Yoko Ono 1971
When you go to war, both sides lose totally- Yoko Ono
Remember, our hearts are one. Even when we are at war with each other, our hearts are always beating in unison- Yoko Ono 2009