I wouldn't say marriage is imploding, although many people are reluctant to tie the knot and they favour cohabiting.
One of the reasons, is the high divorce rate and this is especially the case when one party commits infidelity and the higher earning spouse looses a lot of what they consider to be their hard earned cash. This often is so, where the woman is unfaithful.
I've come across several individuals who favour an open marriage, because they don't believe in monogamy or don't believe it's possible.
It's recognised that less people are getting married in today's society and one reason for that, is because women are agreeable to have children without being married. I've spoken with a number of men who say that, they have the family they wanted without being married, so what's the point in actually getting married. It's not something men dream of, in the same way women do on the whole.
I also go into high schools discussing marriage and (the good and bad) it's with married couples for the students to ask questions.
The idea is to speak to the children, before they form such a negative view of marriage, from seeing relationship breakdowns of their parents and other family members and actually see that marriage can be a good thing.
There are also other relationship formats like polyamory, which some favour.