It should be reasonably possible to ascertain whether you and your spouse will have a pleasant or unpleasant future. If the latter, why the fuck (pun intended) would you have children?
Protracted job loss? Major illness? Death of a child? War?
There are a lot of variables that go into the success of a marriage that can't be predicted, especially over a 20+ year timeframe. The idea that you can reliably predict if someone'll be happy in their marriage decades later is... unsupported.
