But in our culture isn't it also assumed that the marriage will end someday? I once overheard the mother of the groom saying how much she loved her new daughter-in-law and thought that she would make a great first-wife for her son!
Not in my culture, I don't know about yours.
> I once overheard the mother of the groom saying how much she loved her new daughter-in-law and thought that she would make a great first-wife for her son!
"I once overheard..." is a fairly thin reed to hang an inference of broad cultural expectation on.
Their marriage, of course, isn't like those.
We humans are really bad at seeing our biases.
A plurality is the largest individual share where there is no majority. Since marriages have only two outcomes (end by death, end by divorce), there is no room for a plurality, only a majority one way or the other. I don't think people falsely assume other outcomes which reduce the biggest share to a mere plurality.
And there is precious little evidence to support that the biggest share (majority or plurality) is to end in divorce.