Okay, it really does seem like even if they're not compatible, they don't fight and such. So I guess there is no divorce in the game.
On a side note, one of my families wouldn't have had children if the father hadn't adopted a child before he wed. Every attempt failed and I never could get them to work long enough to afford baby boost. Well, the adopted child went off to college and here they are in their 50s - and a 3 year old boy showed up on their doorstep and they've adopted him too. He loves to clean. LOL