Isn't it all a bit pointless ?
You've stuck your two fingers up at society. Two sets of two fingers naturally.
You've done this by living together (without benefit of marriage - oh yes, I watch Judge Judy). You've had kids together. You're now, um, getting married ? Why ?
You've tested out each other's reproductive organs - check
You're probably financially committed to each other - check
You've seen each other in all circumstances - check
So, where's the celebration ? Where's the excitement of starting a life together ? Why does the marrying couple want congratulations ?
Isn't it all a bit same-same by now ?
Now, suddenly, you've decided that you will get married after all. How very grown up of you both.