They'll just have to hope that there are therapists around to help them when it all goes South. What if there aren't?
It's funny how people in the past were able to overcome seemingly impossible situations and make a life for themselves. For instance, the old pioneers in the move to the West across America. They almost all started out with nothing, and by the time they stopped moving they still had most of it left, yet they built themselves homes, filled them with children, and generally made lives for themselves.
I suspect that if society imploded around them, most of today's youngsters would have a meltdown for the first week or so, but then those with the will to live would start to pick themselves up and find ways to mitigate the shortcomings of the situation they found themselves in, and move on to create a better life for themselves and their partners.