The trend is that younger people are not getting married.
Thus, if you are never married, it is extraordinarily difficult to get divorced.
In addition, with fewer couples getting married, those who do get married are more committed to the relationship and to the concept of marriage.
Yes I imagine Christian cultural identity has something to do with it.
Conservative Christians (and I suppose Jews and Hindus and Muslims etc I don’t know) would tend to marry rather than fornicate or cohabitate. And they’d be less likely to divorce I assume.
I know conservatives sometimes can divorce without sin so please don’t be offended, all. It’s just rare.