There are so many experienced, heart felt posts I don't know where to start.
Given the overall maturity most of us start with in marriage it is almost a miracle that any of us wind up with marriages intact, I include myself in the lucky group. My Grandma would agree that "I just flat got lucky."

I do notice a couple of trends. People who stay married tend to just accept and not try to change each other; and they try to be good partners for the other, and so are willing to change. I didn't make this up and can provide scientific references if anyone wants them.