Sorry to say that I doubt the validity of your question. It is because almost all the marriage relations I have witnessed so far show the proclivity towards lasting long. I could seldom find any marriage relation ending up prematurely. Maybe that is because of the fact that the country I live in and its wide variety of cultures do celebrate and value the marriages and the new relations formed through them more than anything.
Unlike many western countries, where getting divorce is like you changing your clothes ( No offense, just repeating what my friends in those countries told me), here in India a couple applying for divorce itself is a big news in the region they belong to.
I have nothing against couples applying for divorce if they really need it. I would rather support it saying it is a sign of the society being on its path towards progress. In India, despite couples not opting for divorce, not many are content with their current life and life partner. most of them are living bearing mental tortures and sexual discontentment. Why the hell should one waste the only life he/she got just for the sake of making others happy? Better leave the life that you don't like and go with the life that makes you happy.
If you really are happy with your current relationship you for sure will genuinely love and enjoy the life you got now. Lest, it is unlikely to lead a happy one.
In short, the only reason marriages don't last long is that people are discontent with the life with their current partners and hence desperately need to get separated. Its a sign of collective evolution of the thought processes of hitherto oppressed human minds.