Non-Fiction tracking of 20 real couples for a couple of decades

[Jay]

In the 1990s I read a non-fiction book written by a woman (I believe a psychologist) who tracked 20 couples for a couple of decades. She then wrote about how their relationships unfolded: marriage, children, divorce, second marriages, blended families, etc.

[Kate]

Was the study done in the U.K. or in the U.S.?
I remember something about this study, but I don't think I read the book. I'd be interested in this, and I'll do some looking.

[Lobstergirl, au gratin]

Jay, are you still looking for this or did you find it?