Along with couples realizing they don't have much in common other than raising their kids, sounds like many of these folks are getting to an age where they may be working less or not at all. Then they have even more time to realize that they don't have any common interests. Their kids may also have less time to spend with them as they start their own families and that is a loss of a common pleasure (although having grandkids to spoil could help make up for this).
IDK, maybe some of it is people realizing they are getting towards the ends of their lives and feeling they should be able to do the things they really want to do and try to be really happy with fewer constraints?
IDK, maybe some of it is people realizing they are getting towards the ends of their lives and feeling they should be able to do the things they really want to do and try to be really happy with fewer constraints?