The married family is becoming endangered with now +40% of children born out of wedlock up from 3% in the 1960s.

What happened?

Over the years:

https://www.cnsnews.com/news/article/terence-p-jeffrey/cdc-babies-born-unmarried-women-exceeded-40-8th-straight-year

By age: young mothers under 20 nearly all out of wedlock

https://www.childtrends.org/wp-content/uploads/2016/04/indicator_1460649378.8721.html

Over the years by race. Asians are still hanging on, native and black family is falling apart:

https://en.wikipedia.org/wiki/African-American_family_structure#/media/File:Nonmarital_Birth_Rates_in_the_United_States,_1940-2014.png

Edit: some more info:

Of students in grades 1 through 12, 39 percent (17.7 million) live in homes absent their biological fathers.

http://www.fathers.com/statistics-and-research/the-extent-of-fatherlessness/

Harvard sociologist Robert Sampson has written that “Family structure is one of the strongest, if not the strongest, predictor of variations in urban violence across cities in the United States.” His views are echoed by the eminent criminologists Michael Gottfredson and Travis Hirschi, who have written that “such family measures as the percentage of the population divorced, the percentage of households headed by women, and the percentage of unattached individuals in the community are among the most powerful predictors of crime rates.”

https://ifstudies.org/blog/school-shootings-fathers-divorce-family-structure

And this is a bad thing?!?

"Boys are more likely to steer clear of trouble with the law when they grow up with their father in the home. One Princeton study found that boys raised apart from their fathers were two to three times more likely to end up in jail before they turned 30.

Dads matter for daughters as well. Another study found that girls whose fathers disappeared before the girls turned 6 were about five times more likely to end up pregnant as teenagers than were their peers raised with their fathers in the home."

https://www.nytimes.com/roomfordebate/2013/06/03/what-are-fathers-for/children-are-better-off-with-a-father-than-without-one

Being born out of wedlock is not the same as being born to single parents. My sister was born in 2005 out of wedlock but my mom and step dad are still together 12 years later (and they eventually married too).

Frankly, I don't accept the premise that "The American Family" is falling apart. Family is not synonymous with mother and father, married, in the home with the child. Families can be, and usually are, a lot bigger than that. Also, as mentioned above, a couple does not need the government to recognize their relationship to be in one. And, lets be realistic, at this point in time, marriage is nothing more than a government license to love your partner. So, fuck that shit.

Wedlock doesn't equal a lack of both parents. I've been with my SO for well over a decade and never married.

You're conflating two things.

Do you like having a sibling? 

What kind of question is that? I have a twin brother, so I don't know what it's like not having a sibling.

Being an unmarried adult stopped being unthinkable.

I have to say that I was really surprised by some of those "out of wedlock" numbers.
I had to triple check and make sure they were legitimate.