David Popenoe, one of the early leaders of the pro-marriage movement among sociologists, has a fine interview with Carol Iannone in Academic Questions. In the '80s and '90s Popenoe was criticized for pointing out that marriage decline was leading to family decline. This was against the prevailing wisdom of the day that all family forms were equally good and nothing was declining.
The most interesting point in the interview, I think, is his contention that since about 2000 there has been a climate change in the field, and in educated culture generally. Now it is accepted that families are, indeed, declining. Popenoe says that even liberals who disagree with him about the solution now admit that there is a problem.