May December marriages: more likely to end from death or from divorce?

What is the divorce rate for May December marriages?
We get queries about May December marriages quite a bit. People want to know if these marriages can last or whether they just end in divorce like Wendi and Rupert Murdoch and Tom Cruise and Katie Holmes. The stats are actually quite encouraging. But first, what is a May December Relationship? A May December Relationship is one where there is a huge age gap between the parties. Anything over 12 years is considered a huge age gap and thus qualifies the marriage as a May December marriage. Tom Cruise is about 16 years older than Katie Holmes, for example while Rupert is about 38 years older than Wendi. Obviously, there are huge gaps and then there are huge gaps. The “May” spouse is the young one in the “Spring of their lives.” And the “December” spouse is the old one in the “Winter” of their lives.
Based on our unscientific research into the issue, it would appear that May December marriages can be very stable unions especially when the husband is older. They typically last until the husband, who usually is the older one (except for folks like Joan Collins and Zsa Zsa Gabor) croaks. In rare circumstances, like the Murdoch/Deng marriage, they can implode and end in divorce. But usually after a very long period of matrimony. These May December marriages typically end in death, not divorce. It is death that part them. They seem to take those vows “till death do us part” more seriously than the rest of the population.
What is the glue that holds these marriages together? It may be a coincidence but usually in these situations, the older spouse tends to be very well resourced, meaning they are usually wealthy old men who manage to snag very young, attractive and fertile baby-making wives. It is very rare in society to find an old, unattractive man with no money who is married to a Young, attractive baby-making woman. So the glue, without meaning to be crass, seems to be money. Pure and simple. This is not to call anyone a “gold-digger” but it is to point out quite honestly that in all of these marriages, the older spouse is wealthy and the younger spouse is attractive. And therefore, money (and sex appeal) seems to be the thing that binds these folks together.
 
Here is a random list of famous May December couplings taken from About.com:

Wendi Deng and Rupert Murdoch. Rupert, +38. He filed for divorce in June 2013 after 14 years of marriage.