If it really was a cultural thing, do you honestly think this man would be living six hours away from his parents?

I dont think the oddity arises in the man wanting to see his family often. I generally see my parents every weekend and even during the week sometimes as well. (Despite growing up in the "failed" model of American suburbia.) But my parents live 20 minutes away. This man is driving six hours to see his parents every weekend which is an enormous waste of time, energy & gas. Its bizarre at best to make such a sojourn that often.

Im sure when you were living with your husband's family, having them so present in your lives was a bonus to your relationship in many ways because you had built in help with your kids. For this couple, his need to be with his family every weekend seems to be preventing them from having much of a relationship. What does this woman do every Friday and Saturday night? Who does all the chores and errands that usually happen on weekends?

I agree with Prudie. I dont think moving near his family will help. He has determinedly placed her second for years and years at this point. Moving close would probably only save on gas for him and push her even further out of the loop.