When I first read "nuclear family", I was thinking of some mutated ratkids living in Chernobyl.
I can tell you my opinion on your "nuclear" family project. As people are becoming more independent, not afraid of being shunned by society...society of course doesnt care as much any more....there is no reason to stick around in an unsuitable environment. A lot of women stayed in abusive marriages, because it was the thing to do. Divorces weren't really ok. I dont believe a child has to have both parents around in order to do very well in life. The parent figures of course, do have to provide stability, and make the child feel he has a place in life.
I could probably bore you for awhile with my opinion on it, that is just a bit of how I feel it is.