A real fact: my tantousha has a bride, most people where I work know her. And he has a girfriend there!
Once I asked to my chief, how it can be?! He just said Ah japanese doesn't mind. After married, most of them live together like strangers. Since the husband is paying nice for the married life, it's all ok. He can go out and she can spend his money away.
this is a pretty old fashioned way of thinking.. there was teh general husband is at a business meeting (being payed attention to by bought girls) but today that will get the husband kicked to the curb.. with western trends like divorce showing up, the women in japan don't play so much the traditional roll and will roll the husband out the door if he isn't faithful..
besides there is also the old fashioned.. my husband is gone for a business meeting and has his girl in waiting.. the wife too had a friend in waiting as well.. again, old fashioned..