How did they control for couples that remove themselves from the sample set because they broke up due to bickering (or a correlation with bickering)?
Do they need to? Those are not couples anymore.
Besides, isn't it easy to track couples for several years, and see which humor each other, which bicker, and which break?
If the idea is "what happens while still in the context of a couple" then it doesn't. In fact that's already implicit in that the couple must "age".
Life is sort of a joke, but it takes a bloody long time to get.
As I grow older, I still try to resist those thoughts - I still like to think that there is that big shift ahead, that something life-changing will happen. That this is not all there is.
And I rationalize this to myself by saying - "otherwise what would be the point?"
Anyway, thank you for putting it the way you did. It was another bump for me to accept the inevitable.
Maybe, the big shift would happen once I've accepted! And then it wouldn't matter!
Edit: Yes, I haven't got the joke yet!